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Pezzella N, Bove G, Tammaro R, Franco B. OFD1: One gene, several disorders. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:57-71. [PMID: 35112477 PMCID: PMC9303915 DOI: 10.1002/ajmg.c.31962] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/19/2022] [Accepted: 01/23/2022] [Indexed: 12/14/2022]
Abstract
The OFD1 protein is necessary for the formation of primary cilia and left–right asymmetry establishment but additional functions have also been ascribed to this multitask protein. When mutated, this protein results in a variety of phenotypes ranging from multiorgan involvement, such as OFD type I (OFDI) and Joubert syndromes (JBS10), and Primary ciliary dyskinesia (PCD), to the engagement of single tissues such as in the case of retinitis pigmentosa (RP23). The inheritance pattern of these condition differs from X‐linked dominant male‐lethal (OFDI) to X‐linked recessive (JBS10, PCD, and RP23). Distinctive biological peculiarities of the protein, which can contribute to explain the extreme clinical variability and the genetic mechanisms underlying the different disorders are discussed. The extensive spectrum of clinical manifestations observed in OFD1‐mutated patients represents a paradigmatic example of the complexity of genetic diseases. The elucidation of the mechanisms underlying this complexity will expand our comprehension of inherited disorders and will improve the clinical management of patients.
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Affiliation(s)
- Nunziana Pezzella
- Scuola Superiore Meridionale, Naples, Italy.,Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Guglielmo Bove
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Roberta Tammaro
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Brunella Franco
- Scuola Superiore Meridionale, Naples, Italy.,Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy.,Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy
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Panigrahi I, Ahuja C, Chaudhry C. Indian child with novel variant in OFD1 gene. Am J Med Genet A 2020; 182:2236-2238. [PMID: 32677760 DOI: 10.1002/ajmg.a.61768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/18/2020] [Accepted: 06/19/2020] [Indexed: 11/08/2022]
Abstract
Orofaciodigital syndrome (OFD) can have variable phenotype and presents with oral anomalies, facial dysmorphism, and digital malformations like syndactyly, and polydactyly. Other presentations also include renal and cardiac defects, and central nervous system anomalies like hydrocephalus and cerebellar abnormalities. OFD1 is a X-linked dominant form of the syndrome presenting in females with mutations in CXorf5 or OFD1 gene. We describe a young child with sparse hairs, milia over face and absence of corpus callosum. Next generation sequencing showed frameshift pathogenic variant in the exon 13 of the OFD1 gene, consistent with diagnosis of OFD1.
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Affiliation(s)
- Inusha Panigrahi
- Genetic Metabolic Unit, Department of Pediatrics, APC, PGIMER, Chandigarh, India
| | | | - Chakshu Chaudhry
- Genetic Metabolic Unit, Department of Pediatrics, APC, PGIMER, Chandigarh, India
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Faily S, Perveen R, Chandler K, Clayton-Smith J. Oral-Facial-Digital Syndrome Type 1: Further Clinical and Molecular Delineation in 2 New Families. Cleft Palate Craniofac J 2020; 57:606-615. [PMID: 32064904 DOI: 10.1177/1055665620902880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE Oral-facial-digital syndrome type 1 (OFD1) [OMIM 311200] is a rare genetic disorder associated with congenital anomalies of the oral cavity, face, and digits. This condition is associated with mutations in the OFD1 gene. Our objective was to recruit patients with the OFD1 clinical phenotype without genetic confirmation, aiming to identify genetic variants in the OFD1 gene. DESIGN Three patients from 2 unrelated families were recruited into our study. We employed a variety of genomic techniques on these patients, including candidate gene analysis, array comparative genomic hybridization, whole-exome sequencing, and whole-genome sequencing. RESULTS We investigated 3 affected patients from 2 unrelated families with a clinical diagnosis of OFD1. We discovered a novel pathogenic dominant missense mutation c.635G>C (p.Arg212Pro) in the OFD1 gene in one family. A novel frameshift, loss-of-function mutation c.306delA (p.Glu103LysfsTer42) was detected in the affected patient in the second family. CONCLUSIONS These new genetic variants will add to the spectrum of known OFD1 mutations associated with the OFD1 disorder. Our study also confirms the variable phenotypic presentation of OFD1 and its well-recognized association with central nervous system malformations and renal anomalies. Molecular diagnostic confirmation achieved in these families will have positive implications for their medical management.
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Affiliation(s)
- Sara Faily
- Manchester Centre for Genomic Medicine, University of Manchester, St Mary's Hospital, Manchester, United Kingdom
| | - Rahat Perveen
- Manchester Centre for Genomic Medicine, University of Manchester, St Mary's Hospital, Manchester, United Kingdom
| | - Kate Chandler
- Manchester Centre for Genomic Medicine, University of Manchester, St Mary's Hospital, Manchester, United Kingdom.,Division of Evolution and Genomic Sciences, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Jill Clayton-Smith
- Manchester Centre for Genomic Medicine, University of Manchester, St Mary's Hospital, Manchester, United Kingdom.,Division of Evolution and Genomic Sciences, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
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Al-Qattan MM, Javed K. Variability of expression of oral-facial-digital syndrome type I in 15 Saudi girls: Why is there a high rate of median cleft lip in the phenotype? Plast Surg (Oakv) 2014; 22:229-32. [PMID: 25535458 DOI: 10.4172/plastic-surgery.1000895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND It is well known that the incidence of nonsyndromal cleft lip and palate varies greatly according to ancestry: 0.3 to 0.4 per 1000 live births in blacks, one in 1000 in Caucasians, and two in 1000 in Asians and individuals from the central province of Saudi Arabia. Median cleft lip is a variable feature in oral-facial-digital syndrome type I (OFD-I). OBJECTIVE To test the hypothesis that genetic factors may determine the lip phenotype in OFD-I patients. METHODS A study involving 15 Saudi girls (from the central province of Saudi Arabia) with OFD-I showed a high rate (93.3%) of median cleft lip and palate. This rate in OFD-I patients is known to range from 33% to 56% in Caucasians and also known to be very low in blacks. The authors compared the rate of median cleft lip with or without cleft palate in the Arabian series (93.3%) with the rate in Caucasians and blacks. RESULTS The difference in median cleft lip with or without cleft palate among the three groups was significant. CONCLUSION This supports the hypothesis that ancestral genetic factors may determine the lip phenotype in OFD-I patients.
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Affiliation(s)
- Mohammad M Al-Qattan
- Plastic Surgery Division, King Saud University and Plastic Surgery Division, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - K Javed
- Plastic Surgery Division, King Saud University and Plastic Surgery Division, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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Al-Qattan MM, Javed K. Variability of expression of oral-facial-digital syndrome type I in 15 Saudi girls: Why is there a high rate of median cleft lip in the phenotype? Plast Surg (Oakv) 2014. [DOI: 10.1177/229255031402200413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background It is well known that the incidence of nonsyndromal cleft lip and palate varies greatly according to ancestry: 0.3 to 0.4 per 1000 live births in blacks, one in 1000 in Caucasians, and two in 1000 in Asians and individuals from the central province of Saudi Arabia. Median cleft lip is a variable feature in oral-facial-digital syndrome type I (OFD-I). Objective To test the hypothesis that genetic factors may determine the lip phenotype in OFD-I patients. Methods A study involving 15 Saudi girls (from the central province of Saudi Arabia) with OFD-I showed a high rate (93.3%) of median cleft lip and palate. This rate in OFD-I patients is known to range from 33% to 56% in Caucasians and also known to be very low in blacks. The authors compared the rate of median cleft lip with or without cleft palate in the Arabian series (93.3%) with the rate in Caucasians and blacks. Results The difference in median cleft lip with or without cleft palate among the three groups was significant. Conclusion This supports the hypothesis that ancestral genetic factors may determine the lip phenotype in OFD-I patients.
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Affiliation(s)
- Mohammad M Al-Qattan
- Plastic Surgery Division, King Saud University and Plastic Surgery Division, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - K Javed
- Plastic Surgery Division, King Saud University and Plastic Surgery Division, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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Webb TR, Parfitt DA, Gardner JC, Martinez A, Bevilacqua D, Davidson AE, Zito I, Thiselton DL, Ressa JHC, Apergi M, Schwarz N, Kanuga N, Michaelides M, Cheetham ME, Gorin MB, Hardcastle AJ. Deep intronic mutation in OFD1, identified by targeted genomic next-generation sequencing, causes a severe form of X-linked retinitis pigmentosa (RP23). Hum Mol Genet 2012; 21:3647-54. [PMID: 22619378 DOI: 10.1093/hmg/dds194] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
X-linked retinitis pigmentosa (XLRP) is genetically heterogeneous with two causative genes identified, RPGR and RP2. We previously mapped a locus for a severe form of XLRP, RP23, to a 10.71 Mb interval on Xp22.31-22.13 containing 62 genes. Candidate gene screening failed to identify a causative mutation, so we adopted targeted genomic next-generation sequencing of the disease interval to determine the molecular cause of RP23. No coding variants or variants within or near splice sites were identified. In contrast, a variant deep within intron 9 of OFD1 increased the splice site prediction score 4 bp upstream of the variant. Mutations in OFD1 cause the syndromic ciliopathies orofaciodigital syndrome-1, which is male lethal, Simpson-Golabi-Behmel syndrome type 2 and Joubert syndrome. We tested the effect of the IVS9+706A>G variant on OFD1 splicing in vivo. In RP23 patient-derived RNA, we detected an OFD1 transcript with the insertion of a cryptic exon spliced between exons 9 and 10 causing a frameshift, p.N313fs.X330. Correctly spliced OFD1 was also detected in patient-derived RNA, although at reduced levels (39%), hence the mutation is not male lethal. Our data suggest that photoreceptors are uniquely susceptible to reduced expression of OFD1 and that an alternative disease mechanism can cause XLRP. This disease mechanism of reduced expression for a syndromic ciliopathy gene causing isolated retinal degeneration is reminiscent of CEP290 intronic mutations that cause Leber congenital amaurosis, and we speculate that reduced dosage of correctly spliced ciliopathy genes may be a common disease mechanism in retinal degenerations.
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Affiliation(s)
- Tom R Webb
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
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Chang TC, Klabnik JL, Liu WS. Regional selection acting on the OFD1 gene family. PLoS One 2011; 6:e26195. [PMID: 22022562 PMCID: PMC3193505 DOI: 10.1371/journal.pone.0026195] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 09/22/2011] [Indexed: 02/01/2023] Open
Abstract
The OFD1 (oral-facial-digital, type 1) gene is implicated in several developmental disorders in humans. The X-linked OFD1 (OFD1X) is conserved in Eutheria. Knowledge about the Y-linked paralog (OFD1Y) is limited. In this study, we identified an OFD1Y on the bovine Y chromosome, which is expressed differentially from the bovine OFD1X. Phylogenetic analysis indicated that: a) the eutherian OFD1X and OFD1Y were derived from the pair of ancestral autosomes during sex chromosome evolution; b) the autosomal OFD1 pseudogenes, present in Catarrhini and Murinae, were derived from retropositions of OFD1X after the divergence of primates and rodents; and c) the presence of OFD1Y in the ampliconic region of the primate Y chromosome is an indication that the expansion of the ampliconic region may initiate from the X-degenerated sequence. In addition, we found that different regions of OFD1/OFD1X/OFD1Y are under differential selection pressures. The C-terminal half of OFD1 is under relaxed selection with an elevated Ka/Ks ratio and clustered positively selected sites, whereas the N-terminal half is under stronger constraints. This study provides some insights into why the OFD1X gene causes OFD1 (male-lethal X-linked dominant) and SGBS2 & JSRDs (X-linked recessive) syndromes in humans, and reveals the origin and evolution of the OFD1 family, which will facilitate further clinical investigation of the OFD1-related syndromes.
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Affiliation(s)
- Ti-Cheng Chang
- Department of Dairy and Animal Science, The Center for Reproductive Biology and Health, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- The Integrative Biosciences Program, Bioinformatics and Genomics Option, The Huck Institute of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Jessica L. Klabnik
- Veterinary and Biomedical Department, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Wan-Sheng Liu
- Department of Dairy and Animal Science, The Center for Reproductive Biology and Health, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- The Integrative Biosciences Program, Bioinformatics and Genomics Option, The Huck Institute of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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Diz P, Álvarez-Iglesias V, Feijoo JF, Limeres J, Seoane J, Tomás I, Carracedo A. A novel mutation in the OFD1 (Cxorf5) gene may contribute to oral phenotype in patients with oral-facial-digital syndrome type 1. Oral Dis 2011; 17:610-4. [DOI: 10.1111/j.1601-0825.2011.01823.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Macca M, Franco B. The molecular basis of oral-facial-digital syndrome, type 1. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2010; 151C:318-25. [PMID: 19876934 DOI: 10.1002/ajmg.c.30224] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Oral-facial-digital syndrome type 1 (OFDI; OFD1; OMIM 311200) is a rare developmental disorder transmitted as an X-linked dominant condition with embryonic male lethality. OFD1 is characterized by malformation of the oral cavity, face, and digits. Central nervous system (CNS) abnormalities and cystic kidney disease can also be part of this condition. This disorder is due to mutations in the OFD1 gene that encodes a centrosomal protein localized at the basal bodies at the origin of primary cilia. Characterization of in vitro and in vivo models demonstrated that, similarly to what described for other ciliary proteins, Ofd1 inactivation is associated to defective sonic hedgehog (Shh) and canonical Wnt signaling pathways. Functional studies have demonstrated that OFD1 has a crucial role in the biology of primary cilia thus ascribing this pleiotropic disease to the growing number of disorders associated to dysfunction of primary cilia. OFD1 shares phenotypic similarities with this latter group of disorders, such as cystic kidneys, skeletal, and CNS abnormalities. Future studies will address whether all clinical manifestations of these diseases can be entirely explained by cilia dysfunction or may also be due to direct roles of the proteins involved.
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Affiliation(s)
- Marina Macca
- Department of Pediatrics of the Federico II University of Naples, Italy
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A novel double deletion underscores the importance of characterizing end points of the CFTR large rearrangements. Eur J Hum Genet 2009; 17:1683-7. [PMID: 19436330 DOI: 10.1038/ejhg.2009.73] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Large genomic rearrangements in patients with cystic fibrosis (CF) account for up to 16-24% of CF alleles negative for point mutations in European populations. Herein, we identified a new large rearrangement removing exon 19 in a young CF patient, who hitherto harbored only the F508del mutation. By using LightCycler technology, we successfully and rapidly delineated the deletion end points by determining the relative copy number of a set CFTR sequence from introns 18 to 19. Fine mapping of the sequences bordering its break points was achieved using direct sequencing. We reported the first complex CFTR rearrangement containing two successive deletion events putatively linked. We evidenced the presence of short direct repeats in the vicinity of the deletions suggesting a possible replication slippage model. In this report, we also discussed the putative molecular mechanism and consequences of this complex gene rearrangement, unprecedented in CF. This complex deletion illustrates the importance of delineating the genomic rearrangement to improve our knowledge of the CFTR mutational spectrum and to better understand the molecular mechanism controlling the CFTR expression.
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Thauvin-Robinet C, Cossée M, Cormier-Daire V, Van Maldergem L, Toutain A, Alembik Y, Bieth E, Layet V, Parent P, David A, Goldenberg A, Mortier G, Héron D, Sagot P, Bouvier AM, Huet F, Cusin V, Donzel A, Devys D, Teyssier JR, Faivre L. Clinical, molecular, and genotype-phenotype correlation studies from 25 cases of oral-facial-digital syndrome type 1: a French and Belgian collaborative study. J Med Genet 2006; 43:54-61. [PMID: 16397067 PMCID: PMC2564504 DOI: 10.1136/jmg.2004.027672] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Oral-facial-digital syndrome type 1 (OFD1) is characterised by an X linked dominant mode of inheritance with lethality in males. Clinical features include facial dysmorphism with oral, tooth, and distal abnormalities, polycystic kidney disease, and central nervous system malformations. Large interfamilial and intrafamilial clinical variability has been widely reported, and 18 distinct mutations have been previously reported within OFD1. A French and Belgian collaborative study collected 25 cases from 16 families. OFD1 was analysed using direct sequencing and phenotype-genotype correlation was performed using chi2 test. X inactivation studies were performed on blood lymphocytes. In 11 families, 11 novel mutations, including nine frameshift, one nonsense, and one missense mutation were identified, which spanned nine different exons. A combination of our results with previously reported cases showed that the majority of mutations (65.5%) was located in exons 3, 8, 9, 13, and 16. There was phenotype-genotype correlation between (a) polycystic kidney disease and splice mutations; (b) mental retardation and mutations located in exons 3, 8, 9, 13, and 16; and (c) tooth abnormalities and mutations located in coiled coil domains. Comparing the phenotype of the families with a pathogenic mutation to families with absence of OFD1 mutation, polycystic kidneys and short stature were significantly more frequent in the group with no OFD1 mutation, whereas lingual hamartomas were significantly more frequent in the group with OFD1 mutation. Finally, an X inactivation study showed non-random X inactivation in a third of the samples. Differential X inactivation between mothers and daughters in two families with high intrafamilial variability was of particular interest. Slight phenotype-genotype correlations were established, and X inactivation study showed that skewed X inactivation could be partially involved in the pathogenesis of intrafamilial clinical variability.
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Horn D, Chyrek M, Kleier S, Lüttgen S, Bolz H, Hinkel GK, Korenke GC, Riess A, Schell-Apacik C, Tinschert S, Wieczorek D, Gillessen-Kaesbach G, Kutsche K. Novel mutations in BCOR in three patients with oculo-facio-cardio-dental syndrome, but none in Lenz microphthalmia syndrome. Eur J Hum Genet 2005; 13:563-9. [PMID: 15770227 DOI: 10.1038/sj.ejhg.5201391] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Oculo-facio-cardio-dental (OFCD) syndrome is a rare X-linked dominant condition with male lethality characterized by microphthalmia, congenital cataracts, facial dysmorphic features, congenital heart defects, and dental anomalies. Mutations in BCOR (BCL6 co-repressor) located in Xp11.4 have been described to cause OFCD syndrome. Lenz microphthalmia syndrome is inherited in an X-linked recessive pattern comprising microphthalmia/anophthalmia, mental retardation, malformed ears, digital, skeletal, and urogenital anomalies (synonym: microphthalmia with associated anomalies (MAA)). One locus for MAA has been mapped to Xq27-q28. Nonetheless, linkage and subsequent mutation analysis revealed a single missense mutation (p.P85L) in BCOR in a large family with presumed Lenz microphthalmia syndrome (MAA2). We describe novel mutations in BCOR in three patients with OFCD syndrome, two small deletions (c.2488_2489delAG and c.3286delG) and a submicroscopic deletion of about 60 kb encompassing at least BCOR exons 2-15. No BCOR mutation was detected in eight patients with Lenz microphthalmia syndrome. Our data confirm that BCOR is the causative gene for OFCD syndrome; however, the failure to identify any mutation in patients with Lenz microphthalmia syndrome together with the oligosymptomatic phenotype in the reported MAA2 patients suggest that BCOR is not the major gene for this syndrome.
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Affiliation(s)
- Denise Horn
- Institut für Medizinische Genetik, Charité, Campus Virchow-Klinikum, Berlin, Germany
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Chen JM, Chuzhanova N, Stenson PD, Férec C, Cooper DN. Complex gene rearrangements caused by serial replication slippage. Hum Mutat 2005; 26:125-34. [PMID: 15977178 DOI: 10.1002/humu.20202] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The now-classical model of replication slippage can in principle account for both simple deletions and tandem duplications associated with short direct repeats. Invariably, a single replication slippage event is invoked, irrespective of whether simple deletions or tandem duplications are involved. However, we recently identified three complex duplicational insertions that could also be accounted for by a model of serial replication slippage. We postulate that a sizeable proportion of hitherto inexplicable complex gene rearrangements may be explained by such a model. To test this idea, and to assess the generality of our initial findings, a number of complex gene rearrangements were selected from the Human Gene Mutation Database (HGMD). Some 95% (20/21) of these mutations were found to be explicable by twin or multiple rounds of replication slippage, the sole exception being a double deletion in the F9 gene that is associated with DNA sequences that appear capable of adopting non-B conformations. Of the 20 complex gene rearrangements, 19 (seven simple double deletions, one triple deletion, two double mutational events comprising a simple deletion and a simple insertion, six simple indels that may constitute a novel and non-canonical class of gene conversion, and three complex indels) were compatible with the model of serial replication slippage in cis; the remaining indel in the MECP2 gene, however, appears to have arisen via interchromosomal replication slippage in trans. Our postulate that serial replication slippage may account for a variety of complex gene rearrangements has therefore received broad support from the study of the above diverse series of mutations.
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Affiliation(s)
- Jian-Min Chen
- INSERM U613 - Génétique Moléculaire et Génétique Epidémiologique, Etablissement Français du Sang - Bretagne, Université de Bretagne Occidentale, Centre Hospitalier Universitaire, Brest, France.
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