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Gulsuner S, Stein DJ, Susser ES, Sibeko G, Pretorius A, Walsh T, Majara L, Mndini MM, Mqulwana SG, Ntola OA, Casadei S, Ngqengelele LL, Korchina V, van der Merwe C, Malan M, Fader KM, Feng M, Willoughby E, Muzny D, Baldinger A, Andrews HF, Gur RC, Gibbs RA, Zingela Z, Nagdee M, Ramesar RS, King MC, McClellan JM. Genetics of schizophrenia in the South African Xhosa. Science 2020; 367:569-573. [PMID: 32001654 PMCID: PMC9558321 DOI: 10.1126/science.aay8833] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 12/18/2019] [Indexed: 07/20/2023]
Abstract
Africa, the ancestral home of all modern humans, is the most informative continent for understanding the human genome and its contribution to complex disease. To better understand the genetics of schizophrenia, we studied the illness in the Xhosa population of South Africa, recruiting 909 cases and 917 age-, gender-, and residence-matched controls. Individuals with schizophrenia were significantly more likely than controls to harbor private, severely damaging mutations in genes that are critical to synaptic function, including neural circuitry mediated by the neurotransmitters glutamine, γ-aminobutyric acid, and dopamine. Schizophrenia is genetically highly heterogeneous, involving severe ultrarare mutations in genes that are critical to synaptic plasticity. The depth of genetic variation in Africa revealed this relationship with a moderate sample size and informed our understanding of the genetics of schizophrenia worldwide.
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Affiliation(s)
- S Gulsuner
- Department of Medicine, Department of Genome Sciences, and Department of Psychiatry, University of Washington, Seattle, WA, USA
| | - D J Stein
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - E S Susser
- Mailman School of Public Health, Columbia University, New York, NY, USA
- New York State Psychiatric Institute, New York, NY, USA
| | - G Sibeko
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - A Pretorius
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - T Walsh
- Department of Medicine, Department of Genome Sciences, and Department of Psychiatry, University of Washington, Seattle, WA, USA
| | - L Majara
- Division of Human Genetics, University of Cape Town, Cape Town, South Africa
| | - M M Mndini
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - S G Mqulwana
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - O A Ntola
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - S Casadei
- Department of Medicine, Department of Genome Sciences, and Department of Psychiatry, University of Washington, Seattle, WA, USA
| | - L L Ngqengelele
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - V Korchina
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - C van der Merwe
- Division of Human Genetics, University of Cape Town, Cape Town, South Africa
| | - M Malan
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - K M Fader
- Mailman School of Public Health, Columbia University, New York, NY, USA
| | - M Feng
- Mailman School of Public Health, Columbia University, New York, NY, USA
- New York State Psychiatric Institute, New York, NY, USA
| | - E Willoughby
- Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - D Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - A Baldinger
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - H F Andrews
- Mailman School of Public Health, Columbia University, New York, NY, USA
- New York State Psychiatric Institute, New York, NY, USA
| | - R C Gur
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA, USA
| | - R A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Z Zingela
- Department of Psychology, Rhodes University, Makhanda (Grahamstown), South Africa
- Department of Psychiatry and Human Behavioral Sciences, Walter Sisulu University, Mthatha, South Africa
| | - M Nagdee
- Department of Psychology, Rhodes University, Makhanda (Grahamstown), South Africa
- Department of Psychiatry and Human Behavioral Sciences, Walter Sisulu University, Mthatha, South Africa
| | - R S Ramesar
- Division of Human Genetics, University of Cape Town, Cape Town, South Africa
| | - M-C King
- Department of Medicine, Department of Genome Sciences, and Department of Psychiatry, University of Washington, Seattle, WA, USA.
| | - J M McClellan
- Department of Medicine, Department of Genome Sciences, and Department of Psychiatry, University of Washington, Seattle, WA, USA
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Chimusa ER, Beighton P, Kumuthini J, Ramesar RS. Detecting genetic modifiers of spondyloepimetaphyseal dysplasia with joint laxity in the Caucasian Afrikaner community. Hum Mol Genet 2019; 28:1053-1063. [PMID: 30358852 DOI: 10.1093/hmg/ddy373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/16/2018] [Accepted: 10/17/2018] [Indexed: 12/31/2022] Open
Abstract
Spondyloepimetaphyseal dysplasia with joint laxity (SEMDJL) is an autosomal-recessive skeletal dysplasia. A relatively large number of patients with SEMDJL have been identified in the Caucasian Afrikaans-speaking community in South Africa. We used a combination of Genome-Wide Human Single Nucleotide Polymorphism (SNP) Array 6.0 data and whole exomic data to potentially dissect genetic modifiers associated with SEMDJL in Caucasian Afrikaans-speaking patients. Leveraging the family-based association signal in prioritizing candidate mutations, we identified two potential modifier genes, COL1A2 and MATN1, and replicating previously identified mutation in KIF22. Importantly, our findings of genetic modifier genes and previously identified mutations are layered on the same sub-network implicated in syndromes characterized by skeletal abnormalities and intellectual disability, bone and connective tissue fragility. This study has potentially provided crucial insights in identifying the indirect modifying mutation(s) linked to the true causal mutation associated with SEMDJL. It is a critical lesson that one may use constructively especially when the pace of exomic sequencing of rare disorders continues apace.
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Affiliation(s)
- Emile R Chimusa
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Peter Beighton
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Judit Kumuthini
- Centre for Proteomic and Genomic Research, St. Peter's Square Mall, Cape Town, South Africa
| | - Rajkumar S Ramesar
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Esterhuizen AI, Mefford HC, Ramesar RS, Wang S, Carvill GL, Wilmshurst JM. Dravet syndrome in South African infants: Tools for an early diagnosis. Seizure 2018; 62:99-105. [PMID: 30321769 DOI: 10.1016/j.seizure.2018.09.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/09/2018] [Accepted: 09/13/2018] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Dravet syndrome (DS) is a well-described, severe genetic epileptic encephalopathy with an increased risk of SUDEP. The incidence and genetic architecture of DS in African patients is virtually unknown, largely due to lack of awareness and unavailability of genetic testing. The clinical benefits of the available precision medicine approaches to treatment emphasise the importance of an early, correct diagnosis. We investigated the genetic causes and clinical features of DS in South African children to develop protocols for early, cost-effective diagnosis in the local setting. METHOD We selected 22 South African children provisionally diagnosed with clinical DS for targeted resequencing of DS-associated genes. We sought to identify the clinical features most strongly associated with SCN1A-related DS, using the DS risk score and clinical co-variates under various statistical models. RESULTS Disease-causing variants were identified in 10 of the 22 children: nine SCN1A and one PCDH19. Moreover, we showed that seizure onset before 6 months of age and a clinical DS risk score of >6 are highly predictive of SCN1A-associated DS. Clinical reassessment resulted in a revised diagnosis in 10 of the 12 variant-negative children. CONCLUSION This first genetic study of DS in Africa confirms that de novo SCN1A variants underlie disease in the majority of South African patients. Affirming the predictive value of seizure onset before 6 months of age and a clinical DS risk score of >6 has significant practical implications for the resource-limited setting, presenting simple diagnostic criteria which can facilitate early correct treatment, specialist consultation and genetic testing.
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Affiliation(s)
- Alina I Esterhuizen
- Division of Human Genetics, Institute of Infectious Diseases and Molecular Medicine, Department of Pathology, University of Cape Town, Cape Town, South Africa; National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa.
| | - Heather C Mefford
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA, USA.
| | - Rajkumar S Ramesar
- Division of Human Genetics, Institute of Infectious Diseases and Molecular Medicine, Department of Pathology, University of Cape Town, Cape Town, South Africa; National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa.
| | - Shuyu Wang
- Department of General Medicine, Alfred Health, Victoria, Australia.
| | - Gemma L Carvill
- Ken and Ruth Davee Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA.
| | - Jo M Wilmshurst
- Paediatric Neurology and Neurophysiology, Red Cross Children's War Memorial Hospital, Cape Town, South Africa; School of Child and Adolescent Health, University of Cape Town, South Africa.
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Esterhuizen AI, Carvill GL, Ramesar RS, Kariuki SM, Newton CR, Poduri A, Wilmshurst JM. Clinical Application of Epilepsy Genetics in Africa: Is Now the Time? Front Neurol 2018; 9:276. [PMID: 29770117 PMCID: PMC5940732 DOI: 10.3389/fneur.2018.00276] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/09/2018] [Indexed: 12/25/2022] Open
Abstract
Over 80% of people with epilepsy live in low- to middle-income countries where epilepsy is often undiagnosed and untreated due to limited resources and poor infrastructure. In Africa, the burden of epilepsy is exacerbated by increased risk factors such as central nervous system infections, perinatal insults, and traumatic brain injury. Despite the high incidence of these etiologies, the cause of epilepsy in over 60% of African children is unknown, suggesting a possible genetic origin. Large-scale genetic and genomic research in Europe and North America has revealed new genes and variants underlying disease in a range of epilepsy phenotypes. The relevance of this knowledge to patient care is especially evident among infants with early-onset epilepsies, where early genetic testing can confirm the diagnosis and direct treatment, potentially improving prognosis and quality of life. In Africa, however, genetic epilepsies are among the most under-investigated neurological disorders, and little knowledge currently exists on the genetics of epilepsy among African patients. The increased diversity on the continent may yield unique, important epilepsy-associated genotypes, currently absent from the North American or European diagnostic testing protocols. In this review, we propose that there is strong justification for developing the capacity to offer genetic testing for children with epilepsy in Africa, informed mostly by the existing counseling and interventional needs. Initial simple protocols involving well-recognized epilepsy genes will not only help patients but will give rise to further clinically relevant research, thus increasing knowledge and capacity.
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Affiliation(s)
- Alina I Esterhuizen
- Division of Human Genetics, Department of Pathology, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa.,National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
| | - Gemma L Carvill
- Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Rajkumar S Ramesar
- Division of Human Genetics, Department of Pathology, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa.,National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
| | - Symon M Kariuki
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Charles R Newton
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - Annapurna Poduri
- Department of Neurology, Harvard Medical School, Boston, MA, United States.,Department of Neurology, Epilepsy Genetics Program, Boston Children's Hospital, Boston, MA, United States
| | - Jo M Wilmshurst
- School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.,Paediatric Neurology and Neurophysiology, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
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Glass T, Dalvie MA, Holtman Z, Vorster AA, Ramesar RS, London L. DNA variants and organophosphate neurotoxicity among emerging farmers in the Western Cape of South Africa. Am J Ind Med 2018; 61:11-20. [PMID: 29143350 DOI: 10.1002/ajim.22790] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2017] [Indexed: 11/06/2022]
Abstract
BACKGROUND Previous epidemiological studies investigating modification of organophosphate (OP) neurotoxicity by xenobiotic metabolizing enzymes (XMEs) polymorphisms have produced inconsistent results. METHODS A cross-sectional study of 301 emerging farmers was conducted. Neurotoxicity testing included forward and backward recall, digit span, and vibration sensitivity testing. Questionnaire data included demography, potential confounders, and work history of pesticide exposures. Genomic DNA was analyzed from study participants for DNA variants of two glutathione S-transferases (GSTM1 and GSTT1), N-acetyltransferase 2 (NAT2), and Paraoxonase 1 (PON1). RESULTS There was evidence of OP pesticide neurotoxicity modification by rs1799931 (NAT2), rs662 (PON1), and the null allele of GSTM1 in multivariate analysis. The strongest evidence of modification was observed for rs1799931 (NAT2) on the relationship between pesticide poisoning and impaired vibration sense. CONCLUSIONS DNA variants of NAT2, PON1, and GSTM1 may modify OP neurotoxicity, and this requires further exploration.
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Affiliation(s)
- Tracy Glass
- School of Public Health and Family Medicine; University of Cape Town; Centre for Environmental and Occupational Health Research (CEOHR); Cape Town Western Cape South Africa
| | - Mohamed A. Dalvie
- School of Public Health and Family Medicine; University of Cape Town; Centre for Environmental and Occupational Health Research (CEOHR); Cape Town Western Cape South Africa
| | - Zelda Holtman
- School of Public Health and Family Medicine; University of Cape Town; Centre for Environmental and Occupational Health Research (CEOHR); Cape Town Western Cape South Africa
| | - Anna A. Vorster
- MRC Human Genetics Research Unit; Division of Human Genetics; Institute for Infectious Diseases and Molecular Medicine; Faculty of Health Sciences; Department of Pathology; University of Cape Town; Cape Town South Africa
| | - Rajkumar S. Ramesar
- MRC Human Genetics Research Unit; Division of Human Genetics; Institute for Infectious Diseases and Molecular Medicine; Faculty of Health Sciences; Department of Pathology; University of Cape Town; Cape Town South Africa
| | - Leslie London
- School of Public Health and Family Medicine; University of Cape Town; Centre for Environmental and Occupational Health Research (CEOHR); Cape Town Western Cape South Africa
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Spracklen TF, Vorster AA, Ramma L, Dalvie S, Ramesar RS. Promoter region variation in NFE2L2 influences susceptibility to ototoxicity in patients exposed to high cumulative doses of cisplatin. Pharmacogenomics J 2016; 17:515-520. [PMID: 27457817 DOI: 10.1038/tpj.2016.52] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/06/2016] [Accepted: 05/18/2016] [Indexed: 01/09/2023]
Abstract
Ototoxicity is a disabling reaction to cisplatin chemotherapy. Much of the inter-individual variability in the development of hearing impairment among cisplatin-receiving patients has not been fully accounted for. In particular, little is known about the pharmacogenomics of cisplatin-induced ototoxicity. This study sought to investigate the role of variation in five candidate genes in a cohort of South African cancer patients. Five variants within the candidate genes were genotyped in 214 patients, of which SLC22A2 rs316019 and NFE2L2 rs6721961 associated with reduced rates of ototoxicity. In the patients who were exposed to cumulative cisplatin doses ⩾200 mg m-2 (n=113), the variant rs6721961 associated with ototoxicity according to three different grading scales of hearing loss (ASHA, P=0.005; Chang, P=0.028; CTCAE, P=0.004). The NFE2L2 promotor variant rs6721961 may therefore be protective against hearing loss in cisplatin-receiving cancer patients.
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Affiliation(s)
- T F Spracklen
- MRC Human Genetics Research Unit, Division of Human Genetics, Institute for Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - A A Vorster
- MRC Human Genetics Research Unit, Division of Human Genetics, Institute for Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - L Ramma
- Division of Communication Sciences and Disorders, Groote Schuur Hospital, Cape Town, South Africa
| | - S Dalvie
- Department of Radiation Oncology, Groote Schuur Hospital, Cape Town, South Africa
| | - R S Ramesar
- MRC Human Genetics Research Unit, Division of Human Genetics, Institute for Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Laiyemo AO, Brawley O, Irabor D, Boutall A, Ramesar RS, Madiba TE. Toward colorectal cancer control in Africa. Int J Cancer 2015; 138:1033-4. [PMID: 26355906 DOI: 10.1002/ijc.29843] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 08/27/2015] [Indexed: 12/31/2022]
Affiliation(s)
- Adeyinka O Laiyemo
- Division of Gastroenterology, Department of Medicine, Howard University College of Medicine, Washington, D.C
| | | | - David Irabor
- Department of Surgery, University of Ibadan, Ibadan, Nigeria
| | | | - Rajkumar S Ramesar
- UCT/SA MRC Human Genetics Research Unit, Division of Human Genetics, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
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Spracklen TF, Whitehorn H, Vorster AA, Ramma L, Dalvie S, Ramesar RS. Genetic variation in Otos is associated with cisplatin-induced ototoxicity. Pharmacogenomics 2015; 15:1667-76. [PMID: 25410892 DOI: 10.2217/pgs.14.112] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Ototoxicity is an adverse drug reaction that may limit the effective use of cisplatin chemotherapy. Given the reported in vitro protective role of the gene Otos in response to cisplatin, this study aimed to explore the potential of Otos as a genetic modifier of ototoxicity. PATIENTS & METHODS One hundred South African cisplatin-receiving cancer patients with baseline and follow-up audiometric data were screened for variation in exonic target regions of Otos using direct cycle sequencing. RESULTS A total of 29 genetic variants were identified. The G alleles of Otos rs77124181 (c.-192-182C>G) and rs2291767 (c.-192-22A>G) were over-represented in ototoxicity-free patients (p = 0.022). Cumulative cisplatin dose and anatomical site of cancer were also associated with ototoxicity, while self-reported ethnicity associated with the ototoxic severity. CONCLUSION This study indicates a potentially protective role for the variant G alleles of SNPs rs77124181 and rs2291767 in Otos against the development of cisplatin-induced ototoxicity.
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Affiliation(s)
- Timothy F Spracklen
- MRC Human Genetics Research Unit, Division of Human Genetics, Institute of Infectious Diseases & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa
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Vorster AA, Beighton P, Ramesar RS. Spondyloepimetaphyseal dysplasia with joint laxity (Beighton type); mutation analysis in eight affected South African families. Clin Genet 2014; 87:492-5. [PMID: 24766538 DOI: 10.1111/cge.12413] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/23/2014] [Accepted: 04/24/2014] [Indexed: 11/29/2022]
Abstract
Spondyloepimetaphyseal dysplasia with joint laxity (SEMD-JL), type 1 is an autosomal recessive disorder which has been identified in more than 30 affected children in the Afrikaans-speaking community of South Africa. Sequencing of B3GALT6 revealed a specific mutation, c.235A > G, in homozygous form in four families, while three others were compound heterozygotes for this mutation in combination with the c.200C > T mutation. In addition, a proband from one family carried the c.16C > T mutation combined with c.200C > T. In a series of five Iranian persons, mutations in B3GALT6 have been implicated in a syndrome characterised by skeletal abnormalities with intellectual disability, bone and connective tissue fragility. Other mutations in B3GALT6 resulted in the classical SEMD-JL phenotype in seven Japanese families and in a syndrome which has been likened to a progeroid form of Ehlers-Danlos syndrome (EDS). It is evident that there is considerable intragenic heterogeneity in B3GALT6. One of the mutations, c.200C > T, in the affected South Africans was also present in one of the Japanese persons and the respective phenotypes were identical. The multiplicity of allelic mutations and the phenotypic differences in the affected persons supports the concept that a spectrum of connective tissue disorders is programmed by mutations in B3GALT6.
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Affiliation(s)
- A A Vorster
- MRC Human Genetics Research Unit, Division of Human Genetics, Department of Clinical Laboratory Sciences, Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
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Heathfield L, Lacerda M, Nossek C, Roberts L, Ramesar RS. Erratum: Stargardt disease: towards developing a model to predict phenotype. Eur J Hum Genet 2013. [DOI: 10.1038/ejhg.2013.179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Swart M, Whitehorn H, Ren Y, Smith P, Ramesar RS, Dandara C. PXR and CAR single nucleotide polymorphisms influence plasma efavirenz levels in South African HIV/AIDS patients. BMC Med Genet 2012; 13:112. [PMID: 23173844 PMCID: PMC3523080 DOI: 10.1186/1471-2350-13-112] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 11/12/2012] [Indexed: 12/02/2022]
Abstract
Background This study investigated variation in NR1I2 and NR1I3 and its effect on plasma efavirenz levels in HIV/AIDS patients. Variability in plasma drug levels has largely led research on identifying causative variants in drug metabolising enzyme (DME) genes, with little focus on the nuclear receptor genes NR1I2 and NR1I3, coding for PXR and CAR, respectively, that are involved in regulating DMEs. Methods 464 Bantu-speaking South Africans comprising of HIV/AIDS patients on efavirenz-based treatment (n=301) and 163 healthy subjects were genotyped for 6 SNPs in NR1I2 and NR1I3. 32 of the 301 patients had their DNA binding domains (DBDs) in NR1I2 and NR1I3 sequenced. Results Significantly decreased efavirenz plasma concentrations were observed in patients carrying the NR1I3 rs3003596C/C and T/C genotypes (P=0.015 and P=0.010, respectively). Sequencing resulted in the discovery of a further 13 SNPs, 3 of which are novel variants in the DBD of NR1I2. There were significant differences in the distribution of NR1I2 and NR1I3 SNPs between South Africans when compared to Caucasian, Asian and Yoruba population groups. Conclusion For the realisation of personalised medicine, PXR and CAR genetic variation should be taken into consideration because of their involvement in the regulation of DMEs.
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Affiliation(s)
- Marelize Swart
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
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Patrinos GP, Smith TD, Howard H, Al-Mulla F, Chouchane L, Hadjisavvas A, Hamed SA, Li XT, Marafie M, Ramesar RS, Ramos FJ, de Ravel T, El-Ruby MO, Shrestha TR, Sobrido MJ, Tadmouri G, Witsch-Baumgartner M, Zilfalil BA, Auerbach AD, Carpenter K, Cutting GR, Dung VC, Grody W, Hasler J, Jorde L, Kaput J, Macek M, Matsubara Y, Padilla C, Robinson H, Rojas-Martinez A, Taylor GR, Vihinen M, Weber T, Burn J, Qi M, Cotton RGH, Rimoin D. Human Variome Project country nodes: documenting genetic information within a country. Hum Mutat 2012; 33:1513-9. [PMID: 22753370 DOI: 10.1002/humu.22147] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 06/04/2012] [Indexed: 11/09/2022]
Abstract
The Human Variome Project (http://www.humanvariomeproject.org) is an international effort aiming to systematically collect and share information on all human genetic variation. The two main pillars of this effort are gene/disease-specific databases and a network of Human Variome Project Country Nodes. The latter are nationwide efforts to document the genomic variation reported within a specific population. The development and successful operation of the Human Variome Project Country Nodes are of utmost importance to the success of Human Variome Project's aims and goals because they not only allow the genetic burden of disease to be quantified in different countries, but also provide diagnosticians and researchers access to an up-to-date resource that will assist them in their daily clinical practice and biomedical research, respectively. Here, we report the discussions and recommendations that resulted from the inaugural meeting of the International Confederation of Countries Advisory Council, held on 12th December 2011, during the 2011 Human Variome Project Beijing Meeting. We discuss the steps necessary to maximize the impact of the Country Node effort for developing regional and country-specific clinical genetics resources and summarize a few well-coordinated genetic data collection initiatives that would serve as paradigms for similar projects.
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Affiliation(s)
- George P Patrinos
- Department of Pharmacy, School of Health Sciences, University of Patras, Patras, Greece.
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Roberts LJ, Nossek CA, Greenberg LJ, Ramesar RS. Stargardt macular dystrophy: common ABCA4 mutations in South Africa--establishment of a rapid genetic test and relating risk to patients. Mol Vis 2012; 18:280-9. [PMID: 22328824 PMCID: PMC3275638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 01/28/2012] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Based on the previous indications of founder ATP-binding cassette sub-family A member 4 gene (ABCA4) mutations in a South African subpopulation, the purpose was to devise a mechanism for identifying common disease-causing mutations in subjects with ABCA4-associated retinopathies (AARs). Facilitating patient access to this data and determining the frequencies of the mutations in the South African population would enhance the current molecular diagnostic service offered. METHODS The majority of subjects in this study were of Caucasian ancestry and affected with Stargardt macular dystrophy. The initial cohort consisted of DNA samples from 181 patients, and was screened using the ABCR400 chip. An assay was then designed to screen a secondary cohort of 72 patients for seven of the most commonly occurring ABCA4 mutations in this population. A total of 269 control individuals were also screened for the seven ABCA4 mutations. RESULTS Microarray screening results from a cohort of 181 patients affected with AARs revealed that seven ABCA4 mutations (p.Arg152*, c.768G>T, p.Arg602Trp, p.Gly863Ala, p.Cys1490Tyr, c.5461-10T>C, and p.Leu2027Phe) occurred at a relatively high frequency. The newly designed genetic assay identified two of the seven disease-associated mutations in 28/72 patients in a secondary patient cohort. In the control cohort, 12/269 individuals were found to be heterozygotes, resulting in an estimated background frequency of these mutations in this particular population of 4.46 per 100 individuals. CONCLUSIONS The relatively high detection rate of seven ABCA4 mutations in the primary patient cohort led to the design and subsequent utility of a multiplex assay. This assay can be used as a viable screening tool and to reduce costs and laboratory time. The estimated background frequency of the seven ABCA4 mutations, together with the improved diagnostic service, could be used by counselors to facilitate clinical and genetic management of South African families with AARs.
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Patrinos GP, Al Aama J, Al Aqeel A, Al-Mulla F, Borg J, Devereux A, Felice AE, Macrae F, Marafie MJ, Petersen MB, Qi M, Ramesar RS, Zlotogora J, Cotton RGH. Recommendations for genetic variation data capture in developing countries to ensure a comprehensive worldwide data collection. Hum Mutat 2011; 32:2-9. [PMID: 21089065 PMCID: PMC3058135 DOI: 10.1002/humu.21397] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Developing countries have significantly contributed to the elucidation of the genetic basis of both common and rare disorders, providing an invaluable resource of cases due to large family sizes, consanguinity, and potential founder effects. Moreover, the recognized depth of genomic variation in indigenous African populations, reflecting the ancient origins of humanity on the African continent, and the effect of selection pressures on the genome, will be valuable in understanding the range of both pathological and nonpathological variations. The involvement of these populations in accurately documenting the extant genetic heterogeneity is more than essential. Developing nations are regarded as key contributors to the Human Variome Project (HVP; http://www.humanvariomeproject.org), a major effort to systematically collect mutations that contribute to or cause human disease and create a cyber infrastructure to tie databases together. However, biomedical research has not been the primary focus in these countries even though such activities are likely to produce economic and health benefits for all. Here, we propose several recommendations and guidelines to facilitate participation of developing countries in genetic variation data documentation, ensuring an accurate and comprehensive worldwide data collection. We also summarize a few well-coordinated genetic data collection initiatives that would serve as paradigms for similar projects. Hum Mutat 31:1–8, 2010. © 2010 Wiley-Liss, Inc.
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15
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Hitchins MP, Owens SE, Kwok CT, Godsmark G, Algar UF, Ramesar RS. Identification of new cases of early-onset colorectal cancer with an MLH1 epimutation in an ethnically diverse South African cohort. Clin Genet 2011; 80:428-34. [PMID: 21375527 DOI: 10.1111/j.1399-0004.2011.01660.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Lynch syndrome, characterized by young-onset microsatellite unstable colorectal, endometrial and other cancers, is caused by germline mutations of the mismatch repair genes, most commonly MLH1, MSH2 and MSH6. Constitutional MLH1 epimutations, which manifest as soma-wide methylation and transcriptional silencing of a single allele, have been identified in a subset of patients with a Lynch syndrome phenotype in the absence of a mismatch repair mutation. This study aimed to determine if MLH1 epimutations predispose to the development of young-onset colorectal cancer in an ethnically diverse population of South African subjects. A total of 122 index cases with a diagnosis of colorectal cancer below 50 years of age, who had tested negative for a definitive pathogenic mutation of the key mismatch repair genes, were screened for constitutional MLH1 methylation in their leukocyte DNA. Monoallelic MLH1 epimutations were identified in two sporadic cases (1.6%): a male of black African descent and an Asian Indian female. Few alleles were affected by methylation in the female, indicating mosaicism. These cases provide further evidence of the aetiological role for MLH1 epimutations in cancer development and the requirement for sensitive molecular screening techniques to identify mosaic epimutations. Furthermore, while this mechanism is rare, it affects patients of multiple ethnic origins.
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Affiliation(s)
- M P Hitchins
- Medical Epigenetics Laboratory, Adult Cancer Program, Lowy Cancer Research Centre, University of New South Wales, Sydney, Australia
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16
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Blokhuis MM, Pietersen GE, Goldberg PA, Algar U, Van der Merwe L, Mbatani N, Vorster AA, Ramesar RS. Lynch syndrome: the influence of environmental factors on extracolonic cancer risk in hMLH1 c.C1528T mutation carriers and their mutation-negative sisters. Fam Cancer 2010; 9:357-63. [PMID: 20640520 DOI: 10.1007/s10689-010-9334-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Lynch Syndrome (LS) is a cancer susceptibility syndrome caused mostly by mutations in the mismatch repair genes, hMLH1, hMSH2 and hMSH6. Mutation carriers are at risk of colorectal and endometrial cancer and, less frequently, cancer of the ovaries, stomach, small bowel, hepatobiliary tract, ureter, renal pelvis and brain. The influence of environmental factors on extracolonic cancer risk in LS patients has not been investigated thus far. The aim of this study was to investigate some of these factors in South African females carrying the hMLH1 c.C1528T mutation and their mutation-negative relatives. Data were collected from 87 mutation-positive females and 121 mutation-negative female relatives regarding age, cancer history, hormonal contraceptive use, parity, duration of breast feeding, height, weight and age at first birth, last birth, menarche and menopause. Influence of these factors on cancer risk was analysed by mixed-effects generalised linear models. Extracolonic cancer occurred in 14% (12/87) of mutation-positive females versus 7% (8/121) of mutation-negative females, (P = 0.0279, adjusted for age and relatedness between women). Breast cancer was the most common extracolonic cancer. An association was found for oral contraceptive use and extracolonic cancer risk in mutation-negative females only. No association was found for any of the other risk factors investigated, when adjusted for age. This might be due to the scarcity of extracolonic cancers in our data. Future knowledge on the influence of additional environmental factors on cancer risk in LS females can lead to evidence-based lifestyle advice for mutation carriers, thereby complementing the prevention strategies available today. In addition, it can contribute to an integrated model of cancer aetiology. Therefore, this study should be taken as a thrust for further research.
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Affiliation(s)
- M M Blokhuis
- MRC Human Genetics Research Unit, Institute for Infectious Diseases and Molecular Medicine, Division of Human Genetics, University of Cape Town, Cape Town, South Africa
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Kaput J, Cotton RGH, Hardman L, Watson M, Al Aqeel AI, Al-Aama JY, Al-Mulla F, Alonso S, Aretz S, Auerbach AD, Bapat B, Bernstein IT, Bhak J, Bleoo SL, Blöcker H, Brenner SE, Burn J, Bustamante M, Calzone R, Cambon-Thomsen A, Cargill M, Carrera P, Cavedon L, Cho YS, Chung YJ, Claustres M, Cutting G, Dalgleish R, den Dunnen JT, Díaz C, Dobrowolski S, dos Santos MRN, Ekong R, Flanagan SB, Flicek P, Furukawa Y, Genuardi M, Ghang H, Golubenko MV, Greenblatt MS, Hamosh A, Hancock JM, Hardison R, Harrison TM, Hoffmann R, Horaitis R, Howard HJ, Barash CI, Izagirre N, Jung J, Kojima T, Laradi S, Lee YS, Lee JY, Gil-da-Silva-Lopes VL, Macrae FA, Maglott D, Marafie MJ, Marsh SGE, Matsubara Y, Messiaen LM, Möslein G, Netea MG, Norton ML, Oefner PJ, Oetting WS, O'Leary JC, de Ramirez AMO, Paalman MH, Parboosingh J, Patrinos GP, Perozzi G, Phillips IR, Povey S, Prasad S, Qi M, Quin DJ, Ramesar RS, Richards CS, Savige J, Scheible DG, Scott RJ, Seminara D, Shephard EA, Sijmons RH, Smith TD, Sobrido MJ, Tanaka T, Tavtigian SV, Taylor GR, Teague J, Töpel T, Ullman-Cullere M, Utsunomiya J, van Kranen HJ, Vihinen M, Webb E, Weber TK, Yeager M, Yeom YI, Yim SH, Yoo HS. Planning the human variome project: the Spain report. Hum Mutat 2009; 30:496-510. [PMID: 19306394 PMCID: PMC5879779 DOI: 10.1002/humu.20972] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The remarkable progress in characterizing the human genome sequence, exemplified by the Human Genome Project and the HapMap Consortium, has led to the perception that knowledge and the tools (e.g., microarrays) are sufficient for many if not most biomedical research efforts. A large amount of data from diverse studies proves this perception inaccurate at best, and at worst, an impediment for further efforts to characterize the variation in the human genome. Because variation in genotype and environment are the fundamental basis to understand phenotypic variability and heritability at the population level, identifying the range of human genetic variation is crucial to the development of personalized nutrition and medicine. The Human Variome Project (HVP; http://www.humanvariomeproject.org/) was proposed initially to systematically collect mutations that cause human disease and create a cyber infrastructure to link locus specific databases (LSDB). We report here the discussions and recommendations from the 2008 HVP planning meeting held in San Feliu de Guixols, Spain, in May 2008.
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Affiliation(s)
- Jim Kaput
- Division of Personalised Nutrition and Medicine, FDA/National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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Ivings L, Towns KV, Matin M, Taylor C, Ponchel F, Grainger RJ, Ramesar RS, Mackey DA, Inglehearn CF. Evaluation of splicing efficiency in lymphoblastoid cell lines from patients with splicing-factor retinitis pigmentosa. Mol Vis 2008; 14:2357-66. [PMID: 19096719 PMCID: PMC2603472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 11/24/2008] [Indexed: 11/17/2022] Open
Abstract
PURPOSE Retinitis pigmentosa (RP) is caused by mutations in a variety of genes, most of which have known functions in the retina. However, one of the most perplexing findings of recent retinal genetics research was the discovery of mutations causing dominant RP in four ubiquitously expressed splicing factors. The aim of this study was to use lymphoblast cell lines derived from RP patients to determine whether mutations in two of these splicing factors, PRPF8 and PRPF31, cause measurable deficiencies in pre-mRNA splicing. METHODS cDNA was prepared from lymphoblastoid cell lines derived from RP patients bearing mutations in the splicing factor genes and controls, grown under a variety of conditions. Introns representing the U2 and U12 intron classes, with both canonical and noncanonical donor and acceptor sequences, were analyzed by real-time PCR to measure the ratio of spliced versus unspliced transcripts for these introns. In addition, plasmids encoding the retinal outer segment membrane protein-1 (ROM-1; exon 1 to exon 2) gene, both in the wild-type form and with mutations introduced into the splice donor sites, were transfected into cell lines. The spliced versus unspliced cDNA ratios were measured by real-time RT-PCR. RESULTS Splicing of four canonical U2 introns in the actin beta (ACTB), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), PRPF8, and retinitis pigmentosa GTPase regulator (RPGR) genes was unaffected in PRPF8 mutant cells. However, the splicing efficiency of RPGR intron 9 was significantly decreased in PRPF31 mutant cell lines. In contrast, a consistent decrease in the splicing efficiency of all U12 and noncanonical U2 introns was seen in PRPF8, but not in PRPF31, mutant cells, with statistical significance for STK11 intron 3. CONCLUSIONS In spite of the ubiquitous expression patterns of the genes implicated in splicing factor RP, no pathology has yet been documented outside the retina. The observed differences in splicing efficiency described herein favor the hypothesis that these mutations may have a subpathological effect outside the retina. These observations argue against a defect in some yet to be discovered additional function of these proteins and support the alternative hypothesis that this form of RP does indeed result from aberrant splicing of retinal transcripts.
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Affiliation(s)
- Lenka Ivings
- Section of Ophthalmology and Neuroscience, Leeds Institute of Molecular Medicine, University of Leeds, St James’s University Hospital, Leeds, United Kingdom
| | - Katherine V. Towns
- Section of Ophthalmology and Neuroscience, Leeds Institute of Molecular Medicine, University of Leeds, St James’s University Hospital, Leeds, United Kingdom
| | - M.A. Matin
- Department of Statistics, University of Leeds, Leeds, United Kingdom
| | - Charles Taylor
- Department of Statistics, University of Leeds, Leeds, United Kingdom
| | - Frederique Ponchel
- Section of Musculoskeletal Disease, Leeds Institute of Molecular Medicine, University of Leeds, St James’s University Hospital, Leeds, United Kingdom
| | - Richard J. Grainger
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Rajkumar S. Ramesar
- Department of Human Genetics, University of Cape Town Medical School, Cape Town, South Africa
| | - David A. Mackey
- CERA, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Chris F. Inglehearn
- Section of Ophthalmology and Neuroscience, Leeds Institute of Molecular Medicine, University of Leeds, St James’s University Hospital, Leeds, United Kingdom
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Cotton RGH, Auerbach AD, Axton M, Barash CI, Berkovic SF, Brookes AJ, Burn J, Cutting G, den Dunnen JT, Flicek P, Freimer N, Greenblatt MS, Howard HJ, Katz M, Macrae FA, Maglott D, Möslein G, Povey S, Ramesar RS, Richards CS, Seminara D, Smith TD, Sobrido MJ, Solbakk JH, Tanzi RE, Tavtigian SV, Taylor GR, Utsunomiya J, Watson M. GENETICS. The Human Variome Project. Science 2008; 322:861-2. [PMID: 18988827 PMCID: PMC2810956 DOI: 10.1126/science.1167363] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An ambitious plan to collect, curate, and make accessible information on genetic variations affecting human health is beginning to be realized.
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Affiliation(s)
- Richard G H Cotton
- Genomic Disorders Research Centre, Howard Florey Institute, Melbourne, Australia.
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Savitz JB, van der Merwe L, Stein DJ, Solms M, Ramesar RS. Neuropsychological task performance in bipolar spectrum illness: genetics, alcohol abuse, medication and childhood trauma. Bipolar Disord 2008; 10:479-94. [PMID: 18452444 DOI: 10.1111/j.1399-5618.2008.00591.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Impaired executive and memory function is a putative genetic trait marker of bipolar I disorder (BPD I). Although executive/memory function has been posited to be an endophenotype of BPD I, it is unclear whether this extends to bipolar spectrum illness. It is also unclear to what extent non-genetic factors such as childhood abuse, alcoholism and medication influence neurocognitive function. We assessed the neuropsychological performance of a large cohort of bipolar disorder probands and their affectively ill and healthy family members, while controlling for self-reported childhood sexual and emotional abuse, emotional neglect, alcohol abuse and medication. METHODS A total of 230 largely euthymic participants from 47 families, comprising 49 subjects with BPD I, 19 with bipolar II disorder (BPD II), 44 with recurrent major depression (MDE-R), 33 with a single lifetime episode of depression (MDE-S), 20 with other DSM-IV diagnoses and 65 unaffected relatives, were assessed with a battery of neuropsychological tasks. RESULTS Sexual abuse, emotional abuse and emotional neglect scores were associated with poorer cognitive performance. After controlling for childhood trauma, the BPD I group performed worse than unaffected relatives on tests of visual recall memory as well as verbal recall and recognition memory. In contrast, individuals with BPD II and bipolar spectrum illness did not differ significantly from unaffected relatives. Treatment with lithium and antipsychotic medication was associated with reduced executive and verbal recognition memory function. After controlling for medication and other covariates, only verbal recall memory was significantly impaired in the BPD I cohort. CONCLUSIONS Verbal recall deficits may be one manifestation of a genetically driven dysfunction of frontal-striatal cortical networks in BPD I.
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Affiliation(s)
- Jonathan B Savitz
- Division of Human Genetics, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
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21
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Savitz JB, van der Merwe L, Newman TK, Solms M, Stein DJ, Ramesar RS. The relationship between childhood abuse and dissociation. Is it influenced by catechol-O-methyltransferase (COMT) activity? Int J Neuropsychopharmacol 2008; 11:149-61. [PMID: 17608961 DOI: 10.1017/s1461145707007900] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Dissociation is a failure of perceptual, memorial and emotional integration that is associated with a variety of psychiatric disorders. Dissociative processes are usually attributed to the sequelae of childhood trauma although there are data to suggest that genetic influences are also important. Bipolar disorder (BD), a condition with a strong genetic basis, has also been associated with early psychological trauma. Since childhood trauma is a risk factor for both BD and dissociation, we tested for potential gene-childhood abuse interactions on dissociation in a pilot sample of BD probands and their affected and unaffected relatives (n=178). Dissociation was measured with the Dissociative Experiences Scale (DES II) and childhood maltreatment with the Childhood Trauma Questionnaire (CTQ). The BD and recurrent unipolar depression (MDE-R) groups showed higher levels of self-reported abuse and dissociation than their unaffected relatives. The low-activity Met allele of the Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene was associated with lower levels of self-reported dissociation. Further, the functional catechol-O-methyltransferase (COMT) Val158Met polymorphism interacted significantly with total CTQ abuse scores to impact perceived dissociation. The Val/Val genotype was associated with increasing levels of dissociation in participants exposed to higher levels of childhood trauma. The opposite was observed in people with Met/Met genotypes who displayed decreased dissociation with increasing self-reported childhood trauma. The current findings support the involvement of the COMT Val158Met polymorphism in mediating the relationship between trauma and psychopathology.
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Affiliation(s)
- Jonathan B Savitz
- MRC/UCT Human Genetics Research Unit, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa.
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Anderson DW, Goldberg PA, Algar U, Felix R, Ramesar RS. Mobile colonoscopic surveillance provides quality care for hereditary nonpolyposis colorectal carcinoma families in South Africa. Colorectal Dis 2007; 9:509-14. [PMID: 17477847 DOI: 10.1111/j.1463-1318.2006.01172.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND It is difficult to provide a colonoscopic surveillance service for at-risk family members with hereditary nonpolyposis colorectal carcinoma when many of those family members live in a remote area of South African far from endoscopic services. A mobile surveillance programme was established to service these individuals. OBJECTIVE The aim of this study was to compare the quality of the mobile service to that provided in established endoscopy units. METHOD Ninety-one asymptomatic subjects with known disease-causing mutations underwent 259 colonoscopies. Of these, 171 colonoscopies were performed by a mobile colonoscopy service in small rural hospitals and 88 in established endoscopy units. The quality of the colonoscopic services was measured by completion rate, the rate of detection of colonoscopic abnormalities, histopathological analyses of biopsies, surgical intervention and colorectal cancer deaths. RESULTS The caecum was reached in 96% of all colonoscopies. A significant lesion was detected in 8.8% of colonoscopies. There was no difference in the rate of complete colonoscopy and detection rate of lesions in the established units and the mobile service (both P = 0.6). The rate of detection of early adenocarcinomas was similar (P = 0.17). The colonoscopic screening/surveillance programme meets international standards with a high accuracy (95.75%) and negative predictive value (100%). CONCLUSION The mobile service provides access to colonoscopy in remote areas without compromising the quality of service.
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Affiliation(s)
- D W Anderson
- Colorectal Unit, Department of Surgery, Institute for Infectious Diseases and Molecular Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
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Felix R, Bodmer W, Fearnhead NS, van der Merwe L, Goldberg P, Ramesar RS. GSTM1 and GSTT1 polymorphisms as modifiers of age at diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) in a homogeneous cohort of individuals carrying a single predisposing mutation. Mutat Res 2007; 602:175-81. [PMID: 17087981 DOI: 10.1016/j.mrfmmm.2006.09.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 09/08/2006] [Accepted: 09/19/2006] [Indexed: 11/26/2022]
Abstract
The variability in phenotype that occurs for so-called 'single-gene disorders' may be because of germline alterations in numerous primary and "modifier" genes. Within HNPCC families harbouring the same primary predisposing mutation, differences exist in the site of cancer, age of onset of disease symptoms and, consequently, survival until diagnosis of disease. The current study investigated a cohort of 129 individuals, from 13 different families, who harbour the identical nonsense mutation (C1528T) in the hMLH1 gene, predisposing them primarily to Lynch I syndrome. This cohort was screened for previously described polymorphisms in the glutathione-S-transferase genes, viz. GSTT1 and GSTM1. Male null carriers for both GSTT1 and GSTM1 were approximately three times more at risk of developing cancer at an earlier age when compared to non-null males. This work, particularly because of the relatively large "homogeneous" primary mutation cohort, provides evidence that genotypic changes distinct from the primary 'HNPCC-causing' mutation, influence the survival period until diagnosis of disease. It provides an impetus for expanding the study to include a wider range of candidate modifier genes. Such work may potentially lead to the development of individualised interval screening regimens for individuals with varying modifier genotypes--an attractive option in a resource-poor country.
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Affiliation(s)
- Rebecca Felix
- MRC Research Unit for Human Genetics, Division of Human Genetics, Institute for Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town Medical School, Anzio Road, Observatory 7925, South Africa
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Abstract
Progress in identifying the genetic basis of bipolar affective disorder has been disappointing, most probably because of the genetic and phenotypic heterogeneity of the condition. These setbacks have led to the adoption of alternative strategies such as the use of endophenotypes or intermediate traits to identify those individuals at genetic risk for developing the disorder. Gottesman and Gould [Am J Psychiatry (2003), 160:636], in a review of the endophenotypic concept, have suggested five criteria that should be characteristic of a trait in order for it to qualify as an endophenotype. These five criteria are used in order to assess the viability of using personality traits as endophenotypes for genetic analyses of bipolar disorder. A review of the literature suggests that certain personality traits or temperaments are associated with the illness in a state independent manner, that personality is at least partly heritable, and that various temperaments aggregate in the non-affected relatives of bipolar probands. Nevertheless, it is unclear whether specific personality traits co-segregate with affectively ill individuals. We conclude that personality profiling of probands and their relatives may facilitate molecular genetic work, but given the fact that personality is itself a complex trait, its use as an endophenotype has certain limitations.
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Affiliation(s)
- Jonathan B Savitz
- MRC/UCT Human Genetics Research Unit, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
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Abstract
In studying the genetics of suicide, should personality be used as an endophenotype (an intermediate trait lying somewhere on the developmental pathway from genes to phenotype)?
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Affiliation(s)
- Jonathan B Savitz
- UCT/MRC Human Genetics Research Unit, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
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Savitz JB, Solms M, Ramesar RS. Neurocognitive Function as an Endophenotype for Genetic Studies of Bipolar Affective Disorder. Neuromolecular Med 2005; 7:275-86. [PMID: 16391385 DOI: 10.1385/nmm:7:4:275] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 05/30/2005] [Accepted: 05/30/2005] [Indexed: 11/11/2022]
Abstract
The genetic basis of bipolar affective disorder remains opaque despite years of intensive investigation. One of the most serious difficulties for genetic research is the enormous phenotypic heterogeneity of psychiatric illnesses. As a response to this problem, geneticists have searched for alternative strategies to identify those individuals at genetic risk for developing the disorder. One approach is to use endophenotypes or intermediate traits. Gottesman and Gould (2003), in their discussion of endophenotypes, suggest five criteria that should be characteristic of a trait in order for it to qualify as an endophenotype. These five criteria are used in order to assess the viability of using measures of neuropsychological dysfunction as endophenotypes for genetic studies of bipolar disorder. A review of the literature suggests that executive dysfunction is characteristic of people with bipolar disorder in both the acute and chronic stages of the illness, that neurocognitive function is influenced by genetic factors and that neuropsychological deficits have been reported in the nonaffected relatives of bipolar probands. Nevertheless, it is unclear whether neuropsychological dysfunction co-segregates with affectively ill individuals. We conclude that the use of neurocognitive markers of bipolar illness suffers from a number of serious drawbacks but given the absence of more appropriate endophenotypes, the neuropsychological profiling of probands and their relatives may nevertheless prove to be a worthwhile exercise.
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Affiliation(s)
- Jonathan B Savitz
- MRC/UCT Human Genetics Research Unit, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Werner Beit North, Level 3, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
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Abstract
Alleles of the serotonin transporter gene (SERT) and the dopamine 4 receptor gene (DRD4) were first associated with anxiety-related and novelty-seeking personality traits, respectively, in 1996. These early successes precipitated a flood of research into the genetic basis of personality; a quest that has yet to yield decisive answers. Here, both the theoretical and the empirical evidence implicating specific loci-in particular SERT and DRD4-in the development of personality is evaluated. Despite a paucity of statistically significant results following post-hoc analysis, and an excess of positive results derived from studies with small sample sizes, the existence of a genuine effect is argued for: a gene-personality relationship rendered periodically latent through genetic epistasis, gene-environment interactions, variation in genetic background, and the presence of other confounding variables.
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Affiliation(s)
- Jonathan B Savitz
- MRC/UCT Human Genetics Research Unit, Divison of Human Genetics, University of Cape Town, Cape Town, South Africa.
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Ramesar RS, Roberts L, Rebello G, Goliath R, Vorster A, September A, Ehrenreich L, Gama D, Greenberg J. Retinal degenerative disorders in Southern Africa: a molecular genetic approach. Adv Exp Med Biol 2004; 533:35-40. [PMID: 15180245 DOI: 10.1007/978-1-4615-0067-4_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- R S Ramesar
- MRC Human Genetics Research Unit, Faculty of Health Sciences, University of Cape Town, South Africa.
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29
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September AV, Vorster AA, Ramesar RS, Greenberg LJ. Mutation spectrum and founder chromosomes for the ABCA4 gene in South African patients with Stargardt disease. Invest Ophthalmol Vis Sci 2004; 45:1705-11. [PMID: 15161829 DOI: 10.1167/iovs.03-1167] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To assess the mutation spectrum of ABCA4 underlying Stargardt disease (STGD) in South Africa (SA) and to determine whether there is a single or a few founder chromosomes in SA STGD families. METHODS Sixty-four probands exhibiting the STGD phenotype were screened for mutations in the 50 exons of ABCA4 by single-strand conformational polymorphism-heteroduplex analysis sequencing and restriction fragment length polymorphism analysis. Microsatellite marker haplotyping was used to determine the ancestry in 10 families. RESULTS Fifty-seven ABCA4 disease-associated alleles were identified that comprised 16 different sequence variants, of which two were novel, in 40 individuals of the cohort of 64 subjects. The most common variants identified included the C1490Y, L2027F, R602W, V256splice, R152X, and 2588G-->C mutations. The C1490Y variant was the most common disease-associated variant identified (19/64 subjects) and was absent in 392 control chromosomes. At least 10 ABCA4 disease-associated haplotypes were identified. Two of these haplotypes, which carried the C1490Y mutation, were identified in three unrelated families. CONCLUSIONS Results suggest that ABCA4 is the major gene underlying STGD in the cohort investigated. Five of the six common sequence variants identified were at a higher frequency in the SA cohort than reported in published data on individuals of similar ancestry. The mutation and haplotype data suggests that there are several ancestral haplotypes underlying STGD in SA. There seems to be at least two different origins for the common C1490Y mutation, as well as two for the R602W mutation, thereby suggesting several founder effects for STGD in SA.
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Affiliation(s)
- Alison V September
- Division of Human Genetics, University of Cape Town, Observatory, Cape Town, South Africa
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30
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Abstract
A genetic register for inherited retinal degenerative disorders (RDDs) has been established at the Division of Human Genetics, UCT Medical School, Cape Town, South Africa. The primary role of the register is to monitor the progress of molecular research and to facilitate the efficient delivery of services, including genetic counselling, to respective family members and new patients. The database currently holds information on 1829 subjects. The RDD-specific breakdown of the data are presented.
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Affiliation(s)
- M T Rebello
- Division of Human Genetics, UCT Medical School, Observatory, South Africa.
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31
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Gong Y, Slee RB, Fukai N, Rawadi G, Roman-Roman S, Reginato AM, Wang H, Cundy T, Glorieux FH, Lev D, Zacharin M, Oexle K, Marcelino J, Suwairi W, Heeger S, Sabatakos G, Apte S, Adkins WN, Allgrove J, Arslan-Kirchner M, Batch JA, Beighton P, Black GC, Boles RG, Boon LM, Borrone C, Brunner HG, Carle GF, Dallapiccola B, De Paepe A, Floege B, Halfhide ML, Hall B, Hennekam RC, Hirose T, Jans A, Jüppner H, Kim CA, Keppler-Noreuil K, Kohlschuetter A, LaCombe D, Lambert M, Lemyre E, Letteboer T, Peltonen L, Ramesar RS, Romanengo M, Somer H, Steichen-Gersdorf E, Steinmann B, Sullivan B, Superti-Furga A, Swoboda W, van den Boogaard MJ, Van Hul W, Vikkula M, Votruba M, Zabel B, Garcia T, Baron R, Olsen BR, Warman ML. LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development. Cell 2001; 107:513-23. [PMID: 11719191 DOI: 10.1016/s0092-8674(01)00571-2] [Citation(s) in RCA: 1548] [Impact Index Per Article: 67.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adult
- Animals
- Animals, Outbred Strains
- Bone Density/genetics
- Bone Morphogenetic Protein 2
- Bone Morphogenetic Proteins/pharmacology
- COS Cells
- Child
- Child, Preschool
- Chlorocebus aethiops
- Chromosomes, Human, Pair 11/genetics
- Culture Media, Conditioned/pharmacology
- DNA, Complementary/genetics
- Dishevelled Proteins
- Eye/embryology
- Eye Abnormalities/genetics
- Female
- Genes, Recessive
- Heterozygote
- Humans
- LDL-Receptor Related Proteins
- Low Density Lipoprotein Receptor-Related Protein-5
- Male
- Mesoderm/cytology
- Mice
- Mice, Inbred C57BL
- Organ Culture Techniques
- Osteoblasts/metabolism
- Osteoporosis/genetics
- Phosphoproteins/genetics
- Phosphoproteins/physiology
- Proteins/genetics
- Proteins/physiology
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/physiology
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Receptors, LDL/physiology
- Recombinant Fusion Proteins/physiology
- Recombinant Proteins
- Signal Transduction
- Skull/cytology
- Species Specificity
- Stromal Cells/cytology
- Stromal Cells/drug effects
- Syndrome
- Transfection
- Transforming Growth Factor beta
- Wnt Proteins
- Wnt-5a Protein
- Wnt2 Protein
- Wnt3 Protein
- Wnt4 Protein
- Zebrafish Proteins
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32
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McKie AB, McHale JC, Keen TJ, Tarttelin EE, Goliath R, van Lith-Verhoeven JJ, Greenberg J, Ramesar RS, Hoyng CB, Cremers FP, Mackey DA, Bhattacharya SS, Bird AC, Markham AF, Inglehearn CF. Mutations in the pre-mRNA splicing factor gene PRPC8 in autosomal dominant retinitis pigmentosa (RP13). Hum Mol Genet 2001; 10:1555-62. [PMID: 11468273 DOI: 10.1093/hmg/10.15.1555] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Retinitis pigmentosa (RP) is a genetically heterogeneous disorder characterized by progressive degeneration of the peripheral retina leading to night blindness and loss of visual fields. With an incidence of approximately 1 in 4000, RP can be inherited in X-linked, autosomal dominant or autosomal recessive modes. The RP13 locus for autosomal dominant RP (adRP) was placed on chromosome 17p13.3 by linkage mapping in a large South African adRP family. Using a positional cloning and candidate gene strategy, we have identified seven different missense mutations in the splicing factor gene PRPC8 in adRP families. Three of the mutations cosegregate within three RP13 linked families including the original large South African pedigree, and four additional mutations have been identified in other unrelated adRP families. The seven mutations are clustered within a 14 codon stretch within the last exon of this large 7 kb transcript. The altered amino acid residues at the C-terminus exhibit a high degree of conservation across species as diverse as humans, Arabidopsis and trypanosome, suggesting that some functional significance is associated with this part of the protein. These mutations in this ubiquitous and highly conserved splicing factor offer compelling evidence for a novel pathway to retinal degeneration.
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Affiliation(s)
- A B McKie
- Molecular Medicine Unit, University of Leeds, Clinical Sciences Building, St James' University Hospital, Leeds LS9 7TF, UK
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33
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Bassi MT, Bergen AA, Bitoun P, Charles SJ, Clementi M, Gosselin R, Hurst J, Lewis RA, Lorenz B, Meitinger T, Messiaen L, Ramesar RS, Ballabio A, Schiaffino MV. Diverse prevalence of large deletions within the OA1 gene in ocular albinism type 1 patients from Europe and North America. Hum Genet 2001; 108:51-4. [PMID: 11214907 DOI: 10.1007/s004390000440] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ocular albinism type 1 (OA1) is an X-linked disorder mainly characterized by congenital nystagmus and photodysphoria, moderate to severe reduction of visual acuity, hypopigmentation of the retina, and the presence of macromelanosomes in the skin and eyes. We have previously isolated the gene for OA1 and characterized its protein product as melanosomal membrane glycoprotein displaying structural and functional features of G protein-coupled receptors. We and others have identified mutations of various types within the OA1 gene in patients with this disorder, including deletions and splice site, frameshift, nonsense, and missense mutations. However, different prevalences of large intragenic deletions have been reported, ranging from 10% to 50% in independent studies. To determine whether these differences might be related to the geographic origin of the OA1 families tested, we performed a further extensive mutation analysis study leading to the identification of pathogenic mutations in 30 unrelated OA1 patients mainly from Europe and North America. These results, together with our earlier mutation reports on OA1, allow us to resolve the apparent discrepancies between previous studies and point to a substantial difference in the frequency of large intragenic deletions in European (<10%) compared with North American (>50%) OA1 families. These observations and our overall refinement of point mutation distribution within the OA1 gene have important implications for the molecular diagnosis of OA1 and for the establishment of any mutation detection program for this disorder.
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Affiliation(s)
- M T Bassi
- Telethon Institute of Genetics and Medicine, Milan, Italy
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Ramesar RS, Madden MV, Felix R, Harocopos CJ, Westbrook CA, Jones G, Cruse JP, Goldberg PA. Molecular genetics improves the management of hereditary non-polyposis colorectal cancer. S Afr Med J 2000; 90:709-14. [PMID: 10985134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
BACKGROUND The syndrome of hereditary non-polyposis colorectal cancer (HNPCC) can be diagnosed fairly accurately using clinical criteria and a family history. Identifying HNPCC helps to prevent large-bowel cancer, or allows cancer to be treated at an early stage. Once the syndrome has been diagnosed a family member's risk can be judged approximately from a family tree, or it can now be predicted accurately if the causative mutation is known. OBJECTIVE This study involved attempts to improve the management of a family with HNPCC over a period of 10 years. Clinical diagnostic criteria, colonoscopic surveillance, surgical treatment, genetic counselling, molecular genetic research, and finally predictive genetic testing were applied as they evolved during this time. SUBJECTS AND METHODS A rural general practitioner first noted inherited large-bowel cancer in the family and began screening subjects as they presented, using rigid sigmoidoscopy at the local hospital. At the time that the disorder was recognised as being HNPCC (1987), screening by means of colonoscopy at our university hospital was aimed primarily at first-degree relatives of affected individuals. After realising how many were at risk, screening was brought closer to the family. A team of clinicians and researchers visited the local hospital to identify and counsel those at risk and to perform screening colonoscopy. Family members were recruited for research to find the gene and its mutation that causes the disease, to develop an accurate predictive test and to reduce the number of subjects undergoing surveillance colonoscopies. RESULTS There are approximately 500 individuals in this family. In the 10 years of this study the number of subjects who have been counselled for increased genetic risk or who have requested colonoscopic surveillance for HNPCC in this kindred has increased from 20 to 140. After the causative mutation was found in the hMLH1 gene on chromosome 3, a test for it has reduced the number of subjects who need screening colonoscopy by over 70%. A protocol has been devised to inform family members, to acquire material for research in order to provide genetic counselling for (pre-test and post-test) risk, and to test for the mutation. Eventually, identifying those with the mutation should focus surveillance accurately. CONCLUSIONS The benefits of restricting screening to subjects with the mutation that causes colorectal cancer and of performing operations to prevent cancer are hard to measure accurately. However, it is likely that at least half the family members will be able to avoid colonoscopic screening, some deaths from cancer should be prevented, and the cost of preventing and treating cancer in the family should fall substantially.
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Affiliation(s)
- R S Ramesar
- Department of Human Genetics, Groote Schuur Hospital
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35
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Bassi MT, Ramesar RS, Caciotti B, Winship IM, De Grandi A, Riboni M, Townes PL, Beighton P, Ballabio A, Borsani G. X-linked late-onset sensorineural deafness caused by a deletion involving OA1 and a novel gene containing WD-40 repeats. Am J Hum Genet 1999; 64:1604-16. [PMID: 10330347 PMCID: PMC1377903 DOI: 10.1086/302408] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have identified a novel gene, transducin (beta)-like 1 (TBL1), in the Xp22.3 genomic region, that shows high homology with members of the WD-40-repeat protein family. The gene contains 18 exons spanning approximately 150 kb of the genomic region adjacent to the ocular albinism gene (OA1) on the telomeric side. However, unlike OA1, TBL1 is transcribed from telomere to centromere. Northern analysis indicates that TBL1 is ubiquitously expressed, with two transcripts of approximately 2.1 kb and 6.0 kb. The open reading frame encodes a 526-amino acid protein, which shows the presence of six beta-transducin repeats (WD-40 motif) in the C-terminal domain. The homology with known beta-subunits of G proteins and other WD-40-repeat containing proteins is restricted to the WD-40 motif. Genomic analysis revealed that the gene is either partly or entirely deleted in patients carrying Xp22.3 terminal deletions. The complexity of the contiguous gene-syndrome phenotype shared by these patients depends on the number of known disease genes involved in the deletions. Interestingly, one patient carrying a microinterstitial deletion involving the 3' portion of both TBL1 and OA1 shows the OA1 phenotype associated with X-linked late-onset sensorineural deafness. We postulate an involvement of TBL1 in the pathogenesis of the ocular albinism with late-onset sensorineural deafness phenotype.
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Affiliation(s)
- M T Bassi
- Telethon Institute of Genetics and Medicine, Milan, Italy
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36
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Bardien-Kruger S, Greenberg J, Tubb B, Bryan J, Queimado L, Lovett M, Ramesar RS. Refinement of the RP17 locus for autosomal dominant retinitis pigmentosa, construction of a YAC contig and investigation of the candidate gene retinal fascin. Eur J Hum Genet 1999; 7:332-8. [PMID: 10234509 DOI: 10.1038/sj.ejhg.5200302] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The RP17 locus for autosomal dominant retinitis pigmentosa has previously been mapped to chromosome 17q by linkage analysis. Two unrelated South African families are linked to this locus and the identification of key recombination events assigned the RP17 locus to a 10 cM interval on 17q22. The work reported here refines the mapping of the locus from a 10 cM to a 1 cM interval between the microsatellite markers D17S1604 and D17S948. A physical map of this interval was constructed using information from the Whitehead/MIT YAC contig WC 17.8. Sequence-tagged site (STS) content mapping of seven overlapping YACs from this contig was employed in order to build the map. A BAC library was screened to cover a gap in the YAC contig and two positive BACs were identified. Intragenic polymorphisms in the retinal fascin gene provided evidence for the exclusion of this candidate as the RP17 disease gene.
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Affiliation(s)
- S Bardien-Kruger
- Department of Human Genetics, University of Cape Town, South Africa
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37
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Ballo R, Briggs MD, Cohn DH, Knowlton RG, Beighton PH, Ramesar RS. Multiple epiphyseal dysplasia, ribbing type: A novel point mutation in the COMP gene in a South African family. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1096-8628(19970211)68:4<396::aid-ajmg4>3.0.co;2-k] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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38
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Abstract
The type II collagenopathies include a wide spectrum of phenotypes ranging from mild spondylo epiphyseal dysplasia (SED) to severe achondrogenesis/hypochondrogenesis. Several attempts have been made at providing phenotype-genotype correlations in this group of disorders. In this report we discuss a South African family in which four members have a phenotype resembling Stickler syndrome type 1. Ocular problems and conductive deafness predominate, while skeletal changes resemble those of a mild form of multiple epiphyseal dysplasia (MED). In distinction to the classical form of Stickler syndrome, the affected persons have stubby digits. DNA analysis of the exons of the COL2A1 gene documented a C-T transversion in exon 39, resulting in an Arg704Cys substitution in the triple helical domain of the type II collagen peptide; this nontermination mutation may be indicative of further heterogeneity in the Stickler group of disorders or of a new syndrome amongst the type II collagenopathies.
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Affiliation(s)
- R Ballo
- MRC Research Unit for Medical Genetics and Department of Human Genetics, University of Cape Town Medical School, South Africa
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39
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Goldberg PA, Madden MV, Harocopos C, Felix R, Westbrook C, Ramesar RS. In a resource-poor country, mutation identification has the potential to reduce the cost of family management for hereditary nonpolyposis colorectal cancer. Dis Colon Rectum 1998; 41:1250-3; discussion 1253-5. [PMID: 9788388 DOI: 10.1007/bf02258223] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE Colonoscopic surveillance of family members at risk of hereditary nonpolyposis colorectal cancer is difficult in a resource-poor country because of its expense. For family members who live in remote areas, poor communication and limited access to sophisticated medical care make surveillance even more difficult. The identification of the mutation causing the disease will simplify surveillance. Our aim was to assess the impact of mutation analysis on the management of a South African family with more than 150 members at risk for hereditary nonpolyposis colorectal cancer. METHODS We studied a family that met the Amsterdam criteria for hereditary nonpolyposis colorectal cancer. Colorectal cancer affected 27 members in three generations (evidence from histology in 12, barium enema in 1, and family statements in 14 family members). Leukocyte DNA from family members was tested for linkage to candidate loci for colorectal cancer, and DNA from formalin-fixed cancers from six family members was studied for microsatellite instability. DNA from all available family members was then screened for mutations in the hMLH1 gene. The number of individuals at 50 percent risk was calculated by family pedigree and compared with the number who have the mutation. RESULTS A disease-causing mutation in exon 13 of hMLH1 segregated with the disorder in members of this kindred. Test results of 100 chromosomes from population-matched controls were negative. Sixty family members between the ages of 16 and 50 years are at 50 percent risk for colon cancer by pedigree analysis, but of these, only 26 (43 percent) have the mutation. CONCLUSION A mutation in the DNA repair gene hMLH1 was found in family members with hereditary nonpolyposis colorectal cancer and in some unaffected relatives previously at 50 percent risk, but not in unrelated subjects. The blood test for the mutation will simplify management, counseling, and surveillance and help to establish prophylactic colectomy.
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Affiliation(s)
- P A Goldberg
- Surgical Gastroenterology Unit, Groote Schuur Hospital and University of Cape Town, South Africa
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40
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DeStefano AL, Cupples LA, Arnos KS, Asher JH, Baldwin CT, Blanton S, Carey ML, da Silva EO, Friedman TB, Greenberg J, Lalwani AK, Milunsky A, Nance WE, Pandya A, Ramesar RS, Read AP, Tassabejhi M, Wilcox ER, Farrer LA. Correlation between Waardenburg syndrome phenotype and genotype in a population of individuals with identified PAX3 mutations. Hum Genet 1998; 102:499-506. [PMID: 9654197 DOI: 10.1007/s004390050732] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Waardenburg syndrome (WS) type 1 is an autosomal dominant disorder characterized by sensorineural hearing loss, pigmentary abnormalities of the eye, hair, and skin, and dystopia canthorum. The phenotype is variable and affected individuals may exhibit only one or a combination of several of the associated features. To assess the relationship between phenotype and gene defect, clinical and genotype data on 48 families (271 WS individuals) collected by members of the Waardenburg Consortium were pooled. Forty-two unique mutations in the PAX3 gene, previously identified in these families, were grouped in five mutation categories: amino acid (AA) substitution in the paired domain, AA substitution in the homeodomain, deletion of the Ser-Thr-Pro-rich region, deletion of the homeodomain and the Ser-Thr-Pro-rich region, and deletion of the entire gene. These mutation classes are based on the structure of the PAX3 gene and were chosen to group mutations predicted to have similar defects in the gene product. Association between mutation class and the presence of hearing loss, eye pigment abnormality, skin hypopigmentation, or white forelock was evaluated using generalized estimating equations, which allowed for incorporation of a correlation structure that accounts for potential similarity among members of the same family. Odds for the presence of eye pigment abnormality, white forelock, and skin hypopigmentation were 2, 8, and 5 times greater, respectively, for individuals with deletions of the homeodomain and the Pro-Ser-Thr-rich region compared to individuals with an AA substitution in the homeodomain. Odds ratios that differ significantly from 1.0 for these traits may indicate that the gene products resulting from different classes of mutations act differently in the expression of WS. Although a suggestive association was detected for hearing loss with an odds ratio of 2.6 for AA substitution in the paired domain compared with AA substitution in the homeodomain, this odds ratio did not differ significantly from 1.0.
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Affiliation(s)
- A L DeStefano
- Department of Neurology, Boston University School of Medicine, MA 02118, USA
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41
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Ramesar RS, Bardien S, Beighton P, Bryer A. Expanded CAG repeats in spinocerebellar ataxia (SCA1) segregate with distinct haplotypes in South african families. Hum Genet 1997; 100:131-7. [PMID: 9225982 DOI: 10.1007/s004390050478] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The autosomal dominant late onset spinocerebellar ataxias (SCAs) are genetically heterogeneous. Three genes, SCA1 on 6p, SCA2 on 12q and MJD1 on 14q, have been isolated for SCA1, SCA2 and Machado-Joseph disease (MJD), respectively. In these three autosomal dominant disorders the mutation is an expanded CAG repeat. Evidence for heterogeneity in families not linked to the SCA1, SCA2 and MJD loci is provided by the mapping of SCA loci to chromosomes 16q, 11cen and 3p. A total of 14 South African kindreds and 22 sporadic individuals with SCA were investigated for the expanded SCA1 and MJD repeats. None of the families nor the sporadic individuals showed expansion of the MJD repeat. Expanded SCA1 and CAG repeats were found to cosegregate with the disorder in six of the families tested and were also observed in one sporadic individual with a negative family history of SCA. The use of the microsatellite markers D6S260, D6S89 and D6S274 provided evidence that the expanded SCA1 repeats segregated with three distinct haplotypes in the six families. Use of the highly polymorphic tightly linked microsatellite markers is still important as this stage, particularly where this coincides with the possibility of a homozygous genotype with the trinucleotide repeat marker. Importantly, our molecular findings indicate: (1) an absence of MJD expanded repeats underlying SCA; (2) the major disease in this group is due to mutations in the SCA1 gene; and (3) the familial disorder in the majority population group (i.e. mixed ancestry) in the Western Cape region of South Africa is most likely to be the result of two distinct founder events.
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Affiliation(s)
- R S Ramesar
- Department of Human Genetics, University of Cape Town Medical School, Observatory, South Africa.
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42
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Ballo R, Briggs MD, Cohn DH, Knowlton RG, Beighton PH, Ramesar RS. Multiple epiphyseal dysplasia, ribbing type: a novel point mutation in the COMP gene in a South African family. Am J Med Genet 1997; 68:396-400. [PMID: 9021009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Multiple epiphyseal dysplasia is broadly categorised into the more severe Fairbank and the milder Ribbing types. In this paper we document mild MED in a South African kindred, and demonstrate that heterozygosity for a mutation in the cartilage oligomeric matrix protein (COMP) gene causes the condition. The mutation, C1594G, implies a N523K substitution, altering a residue at the carboxyl-terminal end of the calmodulin-like region of COMP. The identification of this mutation demonstrates that the spectrum of manifestations from mild MED through pseudoachondroplasia can all be produced by structural mutations in COMP.
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Affiliation(s)
- R Ballo
- Department of Human Genetics, University of Cape Town Medical School, South Africa
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43
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Ramesar RS, Greenberg J, Martin R, Goliath R, Bardien S, Mundlos S, Beighton P. Mapping of the gene for cleidocranial dysplasia in the historical Cape Town (Arnold) kindred and evidence for locus homogeneity. J Med Genet 1996; 33:511-4. [PMID: 8782054 PMCID: PMC1050640 DOI: 10.1136/jmg.33.6.511] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cleidocranial dysplasia (CCD) is an autosomal dominant disorder, features of which include a patient anterior fontanelle, a bulging calvarium, hypoplasia or aplasia of the clavicles, a wide public symphysis, dental anomalies, vertebral malformation, and short stature. The Cape Town kindred which is under our genetic management was originally described more than four decades ago and now consists of more than 1000 people. Following reports of rearrangements on chromosomes 6 and 8 in people with CCD, we have carried out linkage analyses between highly information microsatellite dinucleotide repeat markers in the rearranged regions and the disorder in a branch of this South African CCD kindred, consisting of 38 subjects, 18 of whom are affected. Maximum lod scores (at theta = 0.00) of 7.14 (for marker D6S459), 4.32 (TCTE), 4.99 (D6S452), 5.97 (D6S269), and 3.95 (D6S465) confirm linkage of the disorder to the short arm of chromosome 6. Our data indicate that the CCD gene is located within a minimal region of approximately 10 cM flanked by the marker D6S451 distally and D6S466 proximally. This information is vital towards isolating and characterising the gene for CCD, and is being used to construct a physical map of 6p21.1-6p21.3. More importantly, mapping of the locus in the South African kindred of mixed ancestry, in which the "founder" of the disorder was of Chinese origin, suggests that a single locus is responsible for classic CCD.
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Affiliation(s)
- R S Ramesar
- MRC Research Unit for Medical Genetics, Department of Human Genetics, University of Cape Town, Medical School, Observatory, South Africa
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Rubinsztein DC, Amos W, Leggo J, Goodburn S, Ramesar RS, Old J, Bontrop R, McMahon R, Barton DE, Ferguson-Smith MA. Mutational bias provides a model for the evolution of Huntington's disease and predicts a general increase in disease prevalence. Nat Genet 1994; 7:525-30. [PMID: 7951324 DOI: 10.1038/ng0894-525] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Huntington's disease (HD) correlates with abnormal expansion in a block of CAG repeats in the Huntington's disease gene. We have investigated HD evolution by typing CAG alleles in several human populations and in a variety of primates. We find that human alleles have expanded from a shorter ancestral state and exhibit unusual asymmetric length distributions. Computer simulations are used to show that the human state can be derived readily from a primate ancestor, without the need to invoke natural selection. The key element is a simple length-dependent mutational bias towards longer alleles. Our model can explain a number of empirical observations, and predicts an ever-increasing incidence of HD.
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Affiliation(s)
- D C Rubinsztein
- East Anglian Regional Genetics Service Molecular Genetics Laboratory, Addenbrooke's NHS Trust, Cambridge, UK
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Abstract
X-linked ocular albinism with late-onset sensorineural deafness (OASD) is an autonomous disorder that poses significant clinical problems, causing affected individuals to be blind and deaf by early middle age. Classical X-linked ocular albinism (without deafness; OA1) has recently been linked to markers in the Xp22.2-Xp22.3 region of the human genome. In the present report, a large South African family with OASD was investigated at the molecular level and tight linkage was found to the DXS452 locus at Xp22.3 using 25 informative meioses, with a maximum lod score of 7.1 at a recombination fraction of 0.00. These findings suggest that OA1 and OASD are allelic variants or that they may be due to contiguous gene defects.
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Affiliation(s)
- I M Winship
- Department of Human Genetics, University of Cape Town Medical School, South Africa
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Anderson IJ, Tsipouras P, Scher C, Ramesar RS, Martell RW, Beighton P. Spondyloepiphyseal dysplasia, mild autosomal dominant type is not due to primary defects of type II collagen. Am J Med Genet 1990; 37:272-6. [PMID: 1978986 DOI: 10.1002/ajmg.1320370223] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A mild autosomal dominant form of spondyloepiphyseal dysplasia (SED) is present in several generations of a South African family of English stock. This phenotype differs from that of any other previously described. Although type II collagen defects have been found in some families with SED congenita, the phenotype in our family showed discordant segregation with COL2A1 gene associated restriction fragment length polymorphisms (RFLPs), the markers for the structural locus of type II collagen. It is evident that the SED group of disorders is heterogeneous.
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Affiliation(s)
- I J Anderson
- Department of Pediatrics, University of Connecticut Health Center, Farmington
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Abstract
The nucleotide sequence of the recA gene of Thiobacillus ferrooxidans has been determined. No SOS box characteristic of LexA-regulated promoters could be identified in the 196-bp region upstream from the coding region. The cloned T. ferrooxidans recA gene was expressed in Escherichia coli from both the lambda pR and lac promoters. It was not expressed from the 2.2-kb of T. ferrooxidans DNA preceding the gene. The T. ferrooxidans recA gene specifies a protein of 346 amino acids that has 66% and 69% homology to the RecA proteins of E. coli and Pseudomonas aeruginosa, respectively. Most amino acids that have been identified as being of functional importance in the E. coli RecA protein are conserved in the T. ferrooxidans RecA protein. Although some amino acids that have been associated with proteolytic activity have been substituted, the cloned protein has retained protease activity towards the lambda and E. coli LexA repressors.
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Affiliation(s)
- R S Ramesar
- Department of Microbiology, University of Cape Town, Rondebosch, South Africa
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Ramesar RS, Woods DR, Rawlings DE. Cloning and expression in Escherichia coli of a recA-like gene from the acidophilic autotroph Thiobacillus ferrooxidans. J Gen Microbiol 1988; 134:1141-6. [PMID: 3058862 DOI: 10.1099/00221287-134-5-1141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A recombinant plasmid, pRSR100, containing the functional analogue of the Escherichia coli recA gene was isolated from a genomic library of Thiobacillus ferrooxidans ATCC 33020. The plasmid complemented defects in DNA repair and homologous recombination in E. coli recA mutant strains. Antiserum raised against E. coli RecA protein reacted with the native but defective E. coli HB101 RecA protein; it did not react with protein extracts from the recA deletion mutant E. coli JK696, but it reacted with two protein bands in extracts of E. coli JK696(pRSR100). A single band with an apparent Mr equal to the higher-Mr band in E. coli JK696(pRSR100) was detected in T. ferrooxidans cell extracts with the E. coli RecA antiserum.
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Affiliation(s)
- R S Ramesar
- Department of Microbiology, University of Cape Town, Rondebosch, South Africa
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