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Mizen LAM. Demystifying genetic jargon in psychiatry. BJPSYCH ADVANCES 2021. [DOI: 10.1192/bja.2021.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SUMMARY
Genetic testing in psychiatry is becoming more common, but psychiatrists often receive little training in it. Given the pace of change in genetics, understanding the current methods of testing and their associated merits and limitations can therefore be challenging for some. This narrative, written for psychiatrists in the clinic, aims to cut through the jargon and describe current genetic testing techniques and their evolution from previous methods. It discusses benefits and risks of testing, how geneticists decide whether genetic variants are pathogenic, terminology found in genetic test results and how best to support patients with genetic diagnoses. It also describes methods used to study the genetics of polygenic disorders. It is anticipated this will facilitate a greater understanding of genetic testing and promote confidence among psychiatrists to discuss its clinical utility and implications with patients.
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Costa RA, Ferreira IR, Cintra HA, Gomes LHF, Guida LDC. Genotype-Phenotype Relationships and Endocrine Findings in Prader-Willi Syndrome. Front Endocrinol (Lausanne) 2019; 10:864. [PMID: 31920975 PMCID: PMC6923197 DOI: 10.3389/fendo.2019.00864] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/26/2019] [Indexed: 12/13/2022] Open
Abstract
Prader-Willi syndrome (PWS) is a complex imprinting disorder related to genomic errors that inactivate paternally-inherited genes on chromosome 15q11-q13 with severe implications on endocrine, cognitive and neurologic systems, metabolism, and behavior. The absence of expression of one or more genes at the PWS critical region contributes to different phenotypes. There are three molecular mechanisms of occurrence: paternal deletion of the 15q11-q13 region; maternal uniparental disomy 15; or imprinting defects. Although there is a clinical diagnostic consensus criteria, DNA methylation status must be confirmed through genetic testing. The endocrine system can be the most affected in PWS, and growth hormone replacement therapy provides improvement in growth, body composition, and behavioral and physical attributes. A key feature of the syndrome is the hypothalamic dysfunction that may be the basis of several endocrine symptoms. Clinical and molecular complexity in PWS enhances the importance of genetic diagnosis in therapeutic definition and genetic counseling. So far, no single gene mutation has been described to contribute to this genetic disorder or related to any exclusive symptoms. Here we proposed to review individually disrupted genes within the PWS critical region and their reported clinical phenotypes related to the syndrome. While genes such as MKRN3, MAGEL2, NDN, or SNORD115 do not address the full spectrum of PWS symptoms and are less likely to have causal implications in PWS major clinical signs, SNORD116 has emerged as a critical, and possibly, a determinant candidate in PWS, in the recent years. Besides that, the understanding of the biology of the PWS SNORD genes is fairly low at the present. These non-coding RNAs exhibit all the hallmarks of RNA methylation guides and can be incorporated into ribonucleoprotein complexes with possible hypothalamic and endocrine functions. Also, DNA conservation between SNORD sequences across placental mammals strongly suggests that they have a functional role as RNA entities on an evolutionary basis. The broad clinical spectrum observed in PWS and the absence of a clear genotype-phenotype specific correlation imply that the numerous genes involved in the syndrome have an additive deleterious effect on different phenotypes when deficiently expressed.
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Abstract
Although Prader-Willi syndrome (PWS) is a well-described clinical dysmorphic syndrome, DNA testing is required for a definitive diagnosis. A definitive diagnosis can be made in approximately 99% of cases using DNA testing; there are a number of DNA tests that can be used for this purpose, although there is no set standard algorithm of testing. The dilemma arises because of the complex genetic mechanisms at the basis of PWS, which need to be elucidated. To establish the molecular mechanism with a complete work up, involves at least 2 tests. Here we discuss the commonly used tests currently available and suggest a cost-effective approach to diagnostic testing.
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Affiliation(s)
- Arabella Smith
- University of Sydney Clinical School, Children's Hospital at Westmead, Westmead, Australia
| | - Dorothy Hung
- Children's Hospital at Westmead, Sydney Genome Diagnostics (Cytogenetics), Children's Hospital Network, PO Box 4001, Westmead, Australia
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Chen C, Visootsak J, Dills S, Graham JM. Prader-Willi syndrome: an update and review for the primary pediatrician. Clin Pediatr (Phila) 2007; 46:580-91. [PMID: 17522286 DOI: 10.1177/0009922807299314] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Prader-Willi syndrome, the first known human genomic imprinting disorder, is one of the most common micro-deletion syndromes. Prader-Willi syndrome is caused by the absence of certain paternally inherited genes on the long arm of chromosome 15, resulting in a complete absence of the active copy of the genetic information in this region. It is most commonly known for its food-related characteristics of hyperphagia, food-seeking behavior, and consequent obesity. Primary care physicians play an important role in the care of children with Prader-Willi syndrome, from recognizing the presenting signs and symptoms at its various stages to understanding their unique medical, developmental, behavioral, and dietary issues. They can also serve as a valuable source of support and advocacy for the family. This article reviews the current state of knowledge about Prader-Willi syndrome and discusses up-to-date understanding of the management of this condition.
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Affiliation(s)
- Christina Chen
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
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Pomara C, D'Errico S, Riezzo I, de Cillis GP, Fineschi V. Sudden cardiac death in a child affected by Prader-Willi syndrome. Int J Legal Med 2005; 119:153-7. [PMID: 15750809 DOI: 10.1007/s00414-004-0513-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Accepted: 11/18/2004] [Indexed: 10/25/2022]
Abstract
A case of sudden cardiac death in a 3-year-old young male affected by Prader-Willi syndrome, clinically diagnosed and confirmed by means of DNA methylation, is presented. The infant suddenly collapsed at home and was taken apparently unconsciousness by his mother to the emergency clinic where he was pronounced dead. A complete postmortem examination was performed and the histological findings led to the definition of cardiac death with a typical picture of contraction band necrosis. Pulmonary hypoxic alterations are frequently reported as the primary cause of death in PWS cases. In this fatal case according to the macroscopic and microscopic findings, the cause of death was most likely cardiac and possibly related to contraction band necrosis linked with ventricular fibrillation and sudden death.
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Affiliation(s)
- Cristoforo Pomara
- Institute of Legal Medicine, University of Foggia Ospedali Riuniti, Via L. Pinto 1, 71100 Foggia, Italy
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Abstract
The predominance of females segregating chromosome aberrations to their offspring has been explained mostly by selection disadvantage of unbalanced products of spermatogenesis. However, analysis of data from the literature supports the idea that somatic cells of early female embryos are similar to female germ cells in that they are prone to malsegregation. The goal of this study was to compare the sex ratio (male to female ratio) of carriers of presumably mitotic-occurring chromosome abnormalities to identify any sex biases. In examining the literature, we found a female prevalence in cases of mosaicism associated with uniparental disomy (UPD) (26 male individuals/conceptions and 45 female individuals/conceptions, sex ratio is 0.58, significantly different from 1.06 in newborn population, P = 0.0292). This predominance was highest at gestational age <16 week (8 male and 22 female conceptuses, sex ratio is 0.36, significantly different from expected figure of 1.28, P = 0.0025), which diminished at later stages of fetal development indicating potential correction of trisomies predominantly in females. There is a threefold prevalence of 46,XX/45,X mosaics over 46,XY/45,X mosaics in prenatally diagnosed cases, which also suggests a gender-specific postzygotic chromosome loss. The male prevalence in Prader-Willi syndrome with maternal UPD of chromosome 15 also can be explained by sex-specific trisomy correction, with predominant loss of a maternal chromosome causing biparental inheritance and therefore, complete correction of trisomy in females (without UPD). Finally, there is a female predominance in carriers of chromosome rearrangement with pericentromere break (mosaicism for Robertsonian translocation/isochromosome, centric fission, nonacrocentric isochromosome, and whole arm rearrangement), in both prenatal (21 males and 36 females, sex ratio is 0.58, P < 0.0184) and postnatal ill-defined cases (14 males and 35 females, sex ratio is 0.40, P = 0.001). Thus, the findings presented in this paper suggest that, in addition to reduction in male fertility, and to probable selection against abnormal cell line(s), there are two mechanisms that contribute to female preponderance among carriers of mosaicism: sex-specific chromosome loss and sex-specific centromere instability. The data obtained suggest that females may have gonadal mosaicism for aneuploidies and structural rearrangements more often than males. This may lead to the maternal origin bias in offspring with trisomies or structural rearrangements.
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Affiliation(s)
- Natalia V Kovaleva
- St. Petersburg Centre for Medical Genetics, St. Petersburg, Russian Federation.
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McDaniel LD, Zhang B, Kubiczek E, Ritter M, Huang J, Berard C, Leana-Cox J, Schwartz S, Schultz RA. Construction and screening of a cosmid library generated from a somatic cell hybrid bearing human chromosome 15. Genomics 1997; 40:63-72. [PMID: 9070920 DOI: 10.1006/geno.1996.4517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A cosmid library has been constructed with DNA isolated from a mouse/human hybrid cell line designated A15, which was previously characterized and shown to retain chromosome 15 as the only human material. The library was generated and stored as 34 independent pools of primary colonies at 8-10,000 colonies per pool. Screening colonies representing pools of this library by hybridization with a human-specific repetitive probe has facilitated the identification of random clones bearing human inserts. To data, 43 unique clones have been isolated and the inserts mapped by fluorescence in situ hybridization (FISH) to chromosome 15. An STS was generated for each of these clones by end sequencing of the inserts. Two of these clones, c36 and MR23, were mapped by FISH to 15q26.1, and end-sequence data revealed homology to different regions of the FES protooncogene. Sequence generated from the other end of the c36 insert was found to match the previously identified and unmapped coding sequence EST00075. In addition to the identification of such random clones, establishment of the library as pools was expected to facilitate the PCR-based identification of unique clones representing specific regions of chromosome 15. Screening of the library pools with primers specific to the FES region led to the recovery of five independent clones facilitating the development of a cosmid contig encompassing the FES gene. One of the cosmids isolated by PCR-based analysis was derived from the same pool as M23 and was subsequently shown to be identical to M23. The data offer the first report of a chromosome 15 cosmid library and demonstrate the value of utilizing pools to evaluate libraries generated from complex sources like somatic cell hybrids.
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Affiliation(s)
- L D McDaniel
- McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas 75235, USA
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Arrieta I, Nuñez T, Gil A, Flores P, Nanclares GPD, Martiñez B. A case of Prader-Willi syndrome associated with mosaicism: Cytogenetic and FISH study. Genes Genet Syst 1996. [DOI: 10.1266/ggs.71.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Isabel Arrieta
- Department of Animal Biology and Genetics, Faculty of Sciences, University of Basque Country
| | - Teresa Nuñez
- Department of Animal Biology and Genetics, Faculty of Sciences, University of Basque Country
| | - Alberto Gil
- Department of Animal Biology and Genetics, Faculty of Sciences, University of Basque Country
| | - Piedad Flores
- Department of Animal Biology and Genetics, Faculty of Sciences, University of Basque Country
| | | | - Begona Martiñez
- Department of Animal Biology and Genetics, Faculty of Sciences, University of Basque Country
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Papenhausen PR, Mueller OT, Johnson VP, Sutcliffe M, Diamond TM, Kousseff BG. Uniparental isodisomy of chromosome 14 in two cases: an abnormal child and a normal adult. AMERICAN JOURNAL OF MEDICAL GENETICS 1995; 59:271-5. [PMID: 8599348 DOI: 10.1002/ajmg.1320590302] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Uniparental disomy (UPD) of a number of different chromosomes has been found in associated with abnormal phenotypes. A growing body of evidence for an imprinting effect involving chromosome 14 has been accumulating. We report on a case of paternal UPD of chromosome 14 studied in late gestation due to polyhydramnios and a ventral wall hernia. A prenatal karyotype documented a balanced Robertsonian 14:14 translocation. The baby was born prematurely with hairy forehead, retrognathia, mild puckering of the lips and finger contractures. Hypotonia has persisted since birth and at age one year, a tracheostomy for laryngomalacia and gastrostomy for feeding remain necessary. Absence of maternal VNTR polymorphisms and homozygosity of paternal polymorphisms using chromosome 14 specific probes at D14S22 and D14S13 loci indicated paternal uniparental isodisomy (pUPID). Parental chromosomes were normal. We also report on a case of maternal UPD in a normal patient with a balanced Robertsonian 14:14 translocation and a history of multiple miscarriages. Five previous reports of chromosome 14 UPD suggest that an adverse developmental effect may be more severe whenever the UPD is paternal in origin. This is the second reported patient with paternal UPD and the fifth reported with maternal UPD, and only few phenotypic similarities are apparent. Examination of these chromosome 14 UPD cases of maternal and paternal origin suggests that there are syndromic imprinting effects.
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Affiliation(s)
- P R Papenhausen
- Department of Pediatrics, University of South Florida College of Medicine, Tampa, USA
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Bettio D, Rizzi N, Giardino D, Grugni G, Briscioli V, Selicorni A, Carnevale F, Larizza L. FISH analysis in Prader-Willi and Angelman syndrome patients. AMERICAN JOURNAL OF MEDICAL GENETICS 1995; 56:224-8. [PMID: 7625450 DOI: 10.1002/ajmg.1320560222] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report on a combined high resolution cytogenetic and fluorescent in situ hybridization study (FISH) on 15 Prader-Willi syndrome (PWS) and 14 Angelman syndrome (AS) patients. High resolution banding showed a microdeletion in the 15q11-q13 region in 7 out of 15 PWS patients, and FISH analysis of the D15S11 and SNRPN cosmids demonstrated absence of the critical region in three additional cases. Likewise 8 out of 14 AS patients were found to be deleted with FISH, using the GABRB3 specific cosmid, whereas only 4 of them had a cytogenetically detectable deletion.
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Affiliation(s)
- D Bettio
- Laboratorio di Citogenetica, Centro Auxologico Italiano, Milan
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Affiliation(s)
- M D Donaldson
- Department of Child Health, Fraser of Allander Unit, (Neurology and Child Development), Yorkhill, Glasgow
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Nicholls RD. Genomic imprinting and uniparental disomy in Angelman and Prader-Willi syndromes: a review. AMERICAN JOURNAL OF MEDICAL GENETICS 1993; 46:16-25. [PMID: 8388169 DOI: 10.1002/ajmg.1320460106] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Although Angelman (AS) and Prader-Willi (PWS) syndromes are human genetic disorders with distinctly different developmental and neurobehavioural phenotypes, they both have abnormalities in inheritance of chromosome 15q11-q13. Whether AS or PWS arises depends on the parental origin of a deletion or uniparental disomy (the inheritance of 2 copies of a genetic locus from only one parent) for 15q11-q13. Normal development requires a genetic contribution for this genetic region from both a male and a female parent. The dependence on parental origin implies that genes in human 15q11-q13 have distinct functions depending upon epigenetic, parent-of-origin differences, known as genomic imprinting. Here, I review the role of uniparental disomy and genomic imprinting in the pathogenesis of AS and PWS, and briefly discuss phenotype-genotype correlations using candidate genes and mouse models, in particular for hypopigmentation.
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Affiliation(s)
- R D Nicholls
- Department of Neuroscience, University of Florida College of Medicine, Gainesville 32610
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Freeman SB, May KM, Pettay D, Fernhoff PM, Hassold TJ. Paternal uniparental disomy in a child with a balanced 15;15 translocation and Angelman syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1993; 45:625-30. [PMID: 8456836 DOI: 10.1002/ajmg.1320450522] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Chromosome 15 (15q11-q13) abnormalities cause two distinct conditions, Angelman syndrome (AS) and Prader-Willi syndrome (PWS). We present the first case of a child with a balanced 15;15 translocation and AS in whom molecular studies were crucial in confirming a diagnosis. DNA polymorphisms demonstrated paternal uniparental disomy for chromosome 15, consistent with the diagnosis of AS. The molecular studies also showed the patient to be homozygous at all loci for which the father was heterozygous, suggesting that the structural rearrangement was an isochromosome 15q and not a Robertsonian translocation.
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Affiliation(s)
- S B Freeman
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia 30322
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Smith A, Robson L, Neumann A, Mulcahy M, Chabros V, Deng ZM, Woodage T, Trent RJ. Fluorescence in-situ hybridisation and molecular studies used in the characterisation of a Robertsonian translocation (13q15q) in Prader-Willi syndrome. Clin Genet 1993; 43:5-8. [PMID: 8462197 DOI: 10.1111/j.1399-0004.1993.tb04416.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A patient with classical Prader-Willi syndrome was found to have a Robertsonian translocation 45,XY,t(13q15q)mat. On CBG banding, the translocation chromosome had a large centromere with one primary constriction. Using fluorescence in situ hybridisation, positive signals were obtained with chromosome 13 and chromosome 15 centromere probes, proving that the translocation was dicentric. NOR banding was negative in this chromosome, suggesting that the breakpoints were at 13p11 and 15p11. DNA studies showed that, while there was no deletion involving 15(q11-13), maternal uniparental disomy for chromosome 15 was present. We compare our findings with the five other cases of familial Robertsonian translocation PWS that have been reported.
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Affiliation(s)
- A Smith
- Cytogenetics Laboratory, Children's Hospital, Camperdown, New South Wales, Australia
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Mascari MJ, Gottlieb W, Rogan PK, Butler MG, Waller DA, Armour JA, Jeffreys AJ, Ladda RL, Nicholls RD. The frequency of uniparental disomy in Prader-Willi syndrome. Implications for molecular diagnosis. N Engl J Med 1992; 326:1599-607. [PMID: 1584261 PMCID: PMC7556354 DOI: 10.1056/nejm199206113262404] [Citation(s) in RCA: 203] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Prader-Willi syndrome is a genetic disorder characterized by infantile hypotonia, obesity, hypogonadism, and mental retardation, but it is difficult to diagnose clinically in infants and young children. In about two thirds of patients, a cytogenetically visible deletion can be detected in the paternally derived chromosome 15 (15q11q13). Recently, patients with Prader-Willi syndrome have been described who do not have the cytogenetic deletion but instead have two copies of the 15q11q13 region that are inherited from the mother (with none inherited from the father). This unusual form of inheritance is known as maternal uniparental disomy. Using molecular genetic techniques, we sought to determine the frequency of uniparental disomy in Prader-Willi syndrome. METHODS We performed molecular analyses using DNA markers within 15q11q13 and elsewhere on chromosome 15 in 30 patients with Prader-Willi syndrome who had no cytogenetically visible deletion. We also studied their parents. Three patients with Prader-Willi syndrome who had a cytogenetic deletion served as controls. RESULTS In 18 of the 30 patients without a cytogenetic deletion (60 percent), we demonstrated the presence of maternal uniparental disomy for chromosome 15 and its association with advanced maternal age. In another eight patients (27 percent), we identified large molecular deletions. The remaining four patients (13 percent) had evidence of normal biparental inheritance for chromosome 15; three of these patients were the only ones in the study who had some atypical clinical features. CONCLUSIONS In about 20 percent of all cases, Prader-Willi syndrome results from the inheritance of both copies of chromosome 15 from the mother (maternal uniparental disomy). With the combined use of cytogenetic and molecular techniques, the genetic basis of Prader-Willi syndrome can be identified in up to 95 percent of patients.
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Affiliation(s)
- M J Mascari
- Department of Pediatrics, Milton S. Hershey Medical Center, College of Medicine, Pennsylvania State University, Hershey 17033
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Narahara K, Hiramoto K, Murakami M, Miyake S, Tsuji K, Yokoyama Y, Namba H, Ninomiya S, Murakami R, Seino Y. Unique karyotypes in two patients with Prader-Willi syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1992; 42:671-7. [PMID: 1632436 DOI: 10.1002/ajmg.1320420509] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A physical disruption of the Prader-Willi syndrome (PWS) chromosome region is thought to cause PWS. We describe 2 girls with PWS phenotype, who had unique chromosome 15 abnormalities. The first patient showed mosaicism: 45,XX,t(15;15)(qter----p11.1::q11.200----qter)/46,XX,t(15;15)(qter----p1 1.1::q 11.200----qter), +mar. The band 15q11.2 apparently remained intact in the t(15;15) chromosome, and the mar chromosome was considered as r(15) (p11.1q11.1). The second patient had a karyotype of 47,XX,del(15)(q11.200----q11.207), +idic (15)(pter----q11.1::q11.1----pter). The complex breakage and reunion involving the 15q11.2 regions of the father's homologous chromosomes 15 at meiosis appeared to have resulted in the idic(15) and the del(15) chromosomes. These cytogenetic findings suggest that the PWS chromosome region may be localized on the very proximal portion of band 15q11.2.
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Affiliation(s)
- K Narahara
- Department of Pediatrics, Okayama University Medical School, Japan
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Casamassima AC, Shapiro LR, Wilmot PL, Smith KB. Prader-Willi syndrome and Robertsonian translocations involving chromosome 15. Clin Genet 1991; 39:294-7. [PMID: 1817468 DOI: 10.1111/j.1399-0004.1991.tb03028.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A case of Prader-Willi syndrome is presented in which high resolution chromosome analysis revealed not only a familial Robertsonian translocation [t(13q15q)], but also a del(15) (q11.2q13) of the chromosome 15 not involved in the translocation. While there have been numerous reports of Robertsonian translocations involving chromosome 15 in patients with Prader-Willi syndrome, in this case, the Robertsonian translocation was shown to be unrelated to the clinical findings.
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Affiliation(s)
- A C Casamassima
- Department of Pediatrics, New York Medical College, Valhalla
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20
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Hennekam RC. Chromosomal localisation of the Rubinstein-Taybi syndrome? AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:634-5. [PMID: 2063910 DOI: 10.1002/ajmg.1320380429] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Butler MG. Prader-Willi syndrome: current understanding of cause and diagnosis. AMERICAN JOURNAL OF MEDICAL GENETICS 1990; 35:319-32. [PMID: 2309779 PMCID: PMC5493042 DOI: 10.1002/ajmg.1320350306] [Citation(s) in RCA: 418] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Prader-Willi syndrome (PWS) is characterized by hypotonia, obesity, hypogonadism, short stature, small hands and feet, mental deficiency, a characteristic face, and an interstitial deletion of the proximal long arm of chromosome 15 in about one-half of the patients. The incidence is estimated to be about 1 in 25,000, and PWS is the most common syndromal cause of human obesity. DNA abnormalities, usually deletions or duplications of chromosome 15, have been identified in individuals with PWS with or without recognizable chromosome 15 deletions. Paternal origin of the chromosome 15 deletion by cytogenetic and DNA studies has been found in nearly all PWS individuals studied. No cytogenetic evidence for chromosome breakage has been identified, although an environmental cause (e.g., paternal hydrocarbon-exposed occupations) of the chromosome 15 abnormality has been proposed. PWS patients with the chromosome 15 deletion are more prone to hypopigmentation compared with PWS individuals with normal chromosomes, but no other clinical differences are consistently identified between those with and without the chromosome deletion. Anthropometric, dermatoglyphic, and other clinical findings indicate homogeneity of PWS patients with the chromosome deletion and heterogeneity of the nondeletion patients. A review of our current understanding of the major clinical, cytogenetic, and DNA findings is presented, and clinical manifestations and cytogenetic abnormalities are summarized from the literature.
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Affiliation(s)
- M G Butler
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2578
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Fernandez F, Berry C, Mutton D. Prader-Willi syndrome in siblings, due to unbalanced translocation between chromosomes 15 and 22. Arch Dis Child 1987; 62:841-3. [PMID: 3662590 PMCID: PMC1778472 DOI: 10.1136/adc.62.8.841] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In a family in which the father carried a balanced translocation between chromosomes 15 and 22 two of his children had Prader-Willi syndrome and an unbalanced chromosome complement, having lost the proximal bands from the long arm of chromosome 15. His four other surviving children were normal but carried a balanced translocation.
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25
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Takano T, Nakagome Y, Nagafuchi S, Tanaka F, Nakamura Y, Nagano T, Tanae A, Hibi I. High-resolution cytogenetic studies in patients with Prader-Willi syndrome. Clin Genet 1986; 30:241-8. [PMID: 3791673 DOI: 10.1111/j.1399-0004.1986.tb00603.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We investigated 24 patients with Prader-Willi syndrome by the high-resolution banding technique. Their history and clinical findings were also examined in some detail. Twelve had interstitial deletion of 15q; del(15) (q11.2q13) in 11 cases and del(15) (q11.2q12) in one case. Six revealed normal karyotypes at about 500-850 bands per haploid-set level. In an additional six cases, no deletion was detected. However, we took the results as tentative, as the observed karyotypes were at the 400-bands level. During the course of this study, it was realized that a small deletion in the proximal 15q could be easily overlooked when a mitotic spread around 400-bands or less per haploid-set level was used. There was no distinct difference in the clinical features of patients with interstitial deletion and those with a normal karyotype. Two cases in the latter group lacked some of the typical features of the former group, e.g. poor fetal vigor, neonatal feeding difficulty, hypotonia, and delayed motor development.
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Kalpakian B, Bateman JB, Sparkes RS, Wood GK. Congenital ocular fibrosis syndrome associated with the Prader-Willi syndrome. J Pediatr Ophthalmol Strabismus 1986; 23:170-3. [PMID: 3746591 DOI: 10.3928/0191-3913-19860701-05] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report an 11-year-old boy with both the congenital ocular fibrosis and the Prader-Willi syndromes. Since birth he has had bilateral blepharoptosis and fixed ocular misalignment in downward gaze. Pathological examination of the extraocular muscles showed replacement by fibrous tissue. Additionally, the child had the typical clinical features of the Prader-Willi syndrome including mental retardation, hypotonia, short stature, hypogonadism, and obesity. The Prader-Willi syndrome has been consistently associated with interstitial deletions of the long arm of chromosome 15. Although our patient appeared to have normal chromosomes, he may indeed have an undetectable deletion which may be responsible for both syndromes. We believe that the gene(s) for the congenital ocular fibrosis syndrome may be located near the gene(s) for the Prader-Willi syndrome on the long arm of chromosome 15.
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Butler MG, Meaney FJ, Palmer CG. Clinical and cytogenetic survey of 39 individuals with Prader-Labhart-Willi syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1986; 23:793-809. [PMID: 3953677 PMCID: PMC5494992 DOI: 10.1002/ajmg.1320230307] [Citation(s) in RCA: 255] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In a clinical and cytogenetic survey of 39 individuals with Prader-Labhart-Willi syndrome (PLWS) (23 males and 16 females ranging in age from 2 weeks to 39 years), an interstitial deletion of chromosome 15 (breakpoints q11 and q13) was identified in 21 cases and apparently normal chromosomes in the remainder. Studies of parental chromosome 15 variants showed that the del[15q] was paternal in origin, although chromosomes of both parents were normal. All chromosome deletions were de novo events. Possible causes for the chromosome deletion and the role of chromosome rearrangements in individuals with PLWS are discussed. Clinical characteristics of the deletion and nondeletion groups were recorded and compared with 124 individuals reported in the literature. Individuals with the chromosome deletion were found to have lighter hair, eye, and skin color, greater sun sensitivity, and higher intelligence scores than individuals with normal chromosomes. Correlation studies of metacarpophalangeal pattern profile variables and dermatoglyphic findings indicate apparent homogeneity of the deletion group and heterogeneity of individuals with PLWS and normal chromosomes.
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28
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Schwartz S, Max SR, Panny SR, Cohen MM. Deletions of proximal 15q and non-classical Prader-Willi syndrome phenotypes. AMERICAN JOURNAL OF MEDICAL GENETICS 1985; 20:255-63. [PMID: 2858158 DOI: 10.1002/ajmg.1320200208] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A deletion of the long arm of chromosome 15 (usually involving bands 15q11-q12) has been seen in approximately 50% of Prader-Willi syndrome (PWS) patients [Ledbetter et al, 1982]. However, 14 patients with non-PWS (or atypical PWS) phenotype with 15q deletion indicate great clinical variability. A deletion was found in a propositus with a de novo translocation [45,XY, -15, -22, +rec(15;22) (22pter----22q13.2::15q14----15qter)], who had anomalies not normally observed in PWS patients. Activities of several enzymes mapped to the involved chromosomes were studied in the patient and control individuals. A 50% decrease in the level of arylsulfatase-A confirmed a small deletion in 22q(22q13.2----qter), and additional studies localized more precisely the loci for alpha-mannosidase (cytoplasmic) and beta-galactosidase.
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30
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Veenema H, Beverstock GC, Zvelebil-Tarasevitch N, Doorn JL, van Parys JA, v d Kamp JJ. Duplication in the proximal portion of the long arm of chromosome 15, in a girl without phenotypic features of the Prader-Willi syndrome. Clin Genet 1984; 26:65-8. [PMID: 6467659 DOI: 10.1111/j.1399-0004.1984.tb00791.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The present report concerns a mentally retarded 14-year-old girl with epilepsy. Her karyotype showed a duplication in the proximal portion of the long arm of chromosome 15. Deficiency as well as excess of chromosome 15 material is sometimes associated with Prader-Willi Syndrome. On clinical investigation no symptoms of this syndrome were found in our patient. The abnormal chromosome appeared to have a duplication for the bands q14 and q15.
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Duckett DP, Roberts SH, Davies P. Unbalanced reciprocal translocations in cases of Prader-Willi syndrome. Hum Genet 1984; 67:156-61. [PMID: 6336319 DOI: 10.1007/bf00272991] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A case of Prader-Willi syndrome (PWS) associated with a de novo unbalanced 15q;17q reciprocal translocation presumptively resulting from the tertiary monosomic form of 3:1 meiotic disjunction is described. Twenty-three similar unbalanced translocations have been identified from the literature. The 24 karyotypes are characterised by having 45 chromosomes, monosomy for the pericentromeric region of chromosome 15 (range pter----q11 to q21), and little monosomy of the recipient (non-15) chromosome. Two-thirds of the cases with these karyotypes have phenotypic features of PWS. It seems probable that (i) where unbalanced reciprocal translocations are associated with PWS, they will almost invariably be presumptive segregants of the tertiary monosomic form of 3:1 disjunction and (ii) the majority of cases found with this type of karyotype, particularly it appears when de novo in origin, will be associated with phenotypic features of PWS.
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Mattei MG, Souiah N, Mattei JF. Chromosome 15 anomalies and the Prader-Willi syndrome: cytogenetic analysis. Hum Genet 1984; 66:313-34. [PMID: 6373566 DOI: 10.1007/bf00287636] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The behaviour of chromosome 15 is very different from that of the other acrocentric chromosomes. The cytogenetic characteristics of rearrangements associated with Prader-Willi syndrome (PWS) are analyzed as similar rearrangements irrespective of the associated phenotype (reciprocal translocations of chromosome 15, small bisatellited additional chromosomes, Robertsonian translocations, interstitial deletions, pericentric inversions). This study suggests that: (1) The proximal ( 15q ) region and PWS seem to be indissociable ; (2) chromosome 15 has an indisputable cytogenetic originality which could be related to its histochemical properties. Chromosome 15 constitutive heterochromatin usually contains much 5-methylcytosine-rich DNA and a large amount of each of the four satellite DNAs. Furthermore the existence in the proximal ( 15q ) region of one or several palindromic sequences could be postulated to explain the great lability of this region of chromosome 15.
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Cassidy SB, Thuline HC, Holm VA. Deletion of chromosome 15 (q11-13) in a Prader-Labhart-Willi syndrome clinic population. AMERICAN JOURNAL OF MEDICAL GENETICS 1984; 17:485-95. [PMID: 6336316 DOI: 10.1002/ajmg.1320170211] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Deletion of the long arm of chromosome 15 has recently been reported in a number of patients with the Prader-Labhart-Willi syndrome who were studied with prometaphase banding. We performed cytogenetic analysis on 12 patients with this disorder in whom the clinical diagnosis was certain. A specific cytogenetic anomaly, del(15q11-13) was found in all of the 12 patients. In nine of the 12, the deletion was noted in all cells examined; in two, there was mosaicism, some cells having the deletion and others being normal; one patient had a 7;15 translocation. No clinical differences were evident between individuals with mosaicism for the translocation and those with the typical deletion in all cells examined. The finding that all of our patients with Prader-Labhart-Willi syndrome have a cytogenetic anomaly, with some patients having mosaicism, distinguishes the results of this study from those of previous reports. Prometaphase chromosome analysis is recommended in all individuals clinically suspected of having Prader-Labhart-Willi syndrome and should be considered in hypotonic infants without a specific diagnosis.
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Abstract
A boy with Prader-Willi syndrome was found to have an inversion of chromosome 15,[46,XY,inv(15)(p13q13)]. His unaffected father has an apparently identical inversion of chromosome 15 but in addition has a number 14 chromosome with double satellites. This report supports previous indications of a relationship between a "position effect" and the etiology of Prader-Willi syndrome. However, a more complicated explanation is required in view of the cytogenetic findings in the proband's father.
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Fraccaro M, Zuffardi O, Bühler E, Schinzel A, Simoni G, Witkowski R, Bonifaci E, Caufin D, Cignacco G, Delendi N. Deficiency, transposition, and duplication of one 15q region may be alternatively associated with Prader-Willi (or a similar) syndrome. Analysis of seven cases after varying ascertainment. Hum Genet 1983; 64:388-94. [PMID: 6618490 DOI: 10.1007/bf00292373] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Seven patients are described who have some or all of the symptoms of Prader-Willi syndrome. They were ascertained by varying criteria starting either from the clinical picture or from the identification of a chromosome abnormality involving the proximal portion of the long arm of chromosome 15. The chromosome abnormalities consisted of two balanced translocations (15;18 and 8;15), three unbalanced ones (15;18, 15;19, and 9;15), and one interstitial deletion of bands 15q11 and q12. The seventh case had an unidentified extra chromosome. These data and a review of the literature led to the conclusion that deficiency, transposition, and even duplication of the region(s) 15q11-q13 may all result in a syndrome which is identifiable with or similar to the Prader-Willi syndrome.
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MESH Headings
- Adolescent
- Adult
- Body Height
- Body Weight
- Child
- Child, Preschool
- Chromosome Aberrations
- Chromosome Deletion
- Chromosomes, Human, 13-15
- Chromosomes, Human, 16-18
- Chromosomes, Human, 19-20
- Chromosomes, Human, 6-12 and X
- Consanguinity
- Female
- Humans
- Infant
- Infant, Newborn
- Karyotyping
- Male
- Prader-Willi Syndrome/genetics
- Translocation, Genetic
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Maeda T, Ohno M, Takada M, Matsunobu A, Arai M. Postzygotic D/D translocation homozygosity associated with recurrent abortions. AMERICAN JOURNAL OF MEDICAL GENETICS 1983; 15:389-92. [PMID: 6881208 DOI: 10.1002/ajmg.1320150304] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A Robertsonian translocation involving homologous D chromosomes was found in two cases with a history of recurrent abortions. In the first case the propositus was a 37-year-old phenotypically normal man who had a balanced t(14q14q) translocation. In the second case, a 27-year-old phenotypically normal woman was found to be a balanced t(15q15q) translocation carrier. The recurrent abortions in both cases were probably owing to this translocation.
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Smith A, Dulk GD. Proximal 15q monosomy. J Med Genet 1983. [DOI: 10.1136/jmg.20.3.233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Trevisan C, Saia A, Schergna E, Mantero F. The Prader-Willi syndrome: neuroendocrine study of identical twins. ITALIAN JOURNAL OF NEUROLOGICAL SCIENCES 1983; 4:79-83. [PMID: 6683267 DOI: 10.1007/bf02043442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Identical twins with the Prader-Willi syndrome are reported. Apart from hypogonadism, hypomentia, hypotonia and obesity, they presented shorter than normal stature and the peculiar facies of this syndrome. Both twins also suffered from arterial hypertension with secondary hyperaldosteronism, an abnormality never previously recorded. The endocrinological study showed the presence of hypogonadotrophic hypogonadism in both twins. The GnRH and clomiphene tests suggested a hypothalamic disorder. Although the vast majority of cases with the Prader-Willi syndrome are isolated, the expression of this disorder in two identical twins enhances the possibility of a genetic determination.
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Abstract
The Prader-Willi Syndrome (PWS) has frequently been associated with chromosomal anomalies involving the region 15q11-q12. The first case of this syndrome associated with a de novo translocation involving chromosomes 11 and 15 is reported. The breakpoints were identified as 11q25 and 15q11 or q12[45, XX,t(11;15)(q25;q11-12)], resulting in the deletion of 15pter leads to 15q11-q12. Previously reported cases of PWS associated with translocations are reviewed in relation to the "deletion hypothesis."
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41
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Kousseff BG. The cytogenetic controversy in the Prader-Labhart-Willi syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1982; 13:431-9. [PMID: 7158643 DOI: 10.1002/ajmg.1320130412] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A patient with Prader-Labhart-Willi syndrome (PLWS) was found to have mosaic partial trisomy 15: 46,XY/47,XY, + del(15) (pter leads to q1.3:) in both lymphocytes and fibroblasts. Thus, another novel aberration is added to the spectrum of chromosome abnormalities seen in this syndrome. The spectrum includes deletion of the short arm of chromosome 15, interstitial deletion of 15q1.2, inverted duplication of 15p (tetrasomy 15p), partial trisomy 15 different from that encountered in this patient, and a variety of aberrations involving other chromosomes. A hypothesis that the chromosome aberrations are due to a presumed gene for the PLWS may have merit and could be tested in the laboratory by exposing chromosomes of patients with PLWS to mutagens to search for secondary chromosome derangements.
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42
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Abstract
Three children with Prader-Willi syndrome and chromosome abnormalities affecting chromosome 15 are described and the literature is reviewed. The usefulness of chromosome analysis in the investigation of the floppy infant is illustrated by two of the cases described. Twenty-three other children with similar clinical features had normal chromosomes.
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43
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Abstract
Twenty-four patients, all of them over 15 years, with the Prader-Willi syndrome are described. Obesity, often extreme, associated with an insatiable appetite, was their principal handicap and this was made worse by educational subnormality and hypogonadism. Three of the them developed diabetes. Each attended a special school or an adult training centre. Although most of them were of short stature and had scoliosis, 2 were tall but they even more severely mentally retarded than is usually the case. Nine other patients died aged between 3 and 23 years. The most common cause of death was cor pulmonale.
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44
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Ledbetter DH, Riccardi VM, Airhart SD, Strobel RJ, Keenan BS, Crawford JD. Deletions of chromosome 15 as a cause of the Prader-Willi syndrome. N Engl J Med 1981; 304:325-9. [PMID: 7442771 DOI: 10.1056/nejm198102053040604] [Citation(s) in RCA: 403] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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45
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Fujita H, Sakamoto Y, Hamamoto Y. An extra idic(15p)(q11) chromosome in Prader-Willi syndrome. Hum Genet 1980; 55:409-11. [PMID: 6162774 DOI: 10.1007/bf00290227] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Using a nonfluorescent AT-specific oligopeptide antibiotic, Distamycin A, on DAPI fluorescent banding of human chromosome (DA-DAPI) as described by Schweizer et al. (1978), we have detected an additional idic(15p) chromosome in a patient with typical Prader-Willi syndrome. On the basis of the evidence available in previous studies and of our own present results, we suspect that the fundamental genetic error in the syndrome is not caused by a chromosome aberration but by a gene aberration on chromosome 15.
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46
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Smith A, Noel M. A girl with the Prader-Willi syndrome and Robertsonian translocation 45,XX,t(14;15)(p11;q11) which was present in three normal family members. Hum Genet 1980; 55:271-3. [PMID: 7450770 DOI: 10.1007/bf00291777] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A 21-year-old girl with classical Prader-Willi Syndrome was found to have a 14;15 Robertsonian translocation--45,XX,t(14;15)(p11;q11). This type of Robertsonian translocation was not found in any patient from 8 surveys covering 6144 patients with mental retardation. Chromosome 15 has been involved in translocations in patients with the Prader-Willi Syndrome with greater than expected frequency. This is the first report of a 14;15 translocation and the Prader-Willi Syndrome. The same balanced translocation was present in the patient's mother and 2 normal siblings. Future genetic counselling for these 2 siblings will be difficult.
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47
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Wisniewski LP, Witt ME, Ginsberg-Fellner F, Wilner J, Desnick RJ. Prader-Willi syndrome and a bisatellited derivative of chromosome 15. Clin Genet 1980; 18:42-7. [PMID: 7418253 DOI: 10.1111/j.1399-0004.1980.tb01363.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A de nova bistaellited derivative of chromosome 15, inv dup (15) (pter leads to q11 or 12::p11 or q11 or 12 leads to pter), was identified by multiple banding techniques in a patient with Prader-Willi syndrome. A comparison of familial no. 15 short arm polymorphisms indicated that the extra chromosome was the result of a non-sister chromatid exchange between the paternal no. 15 homologs prior to or during meiosis.
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48
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Mattei MG, Mattei JF, Vidal I, Giraud F. Advantages of silver staining in seven rearrangements of acrocentric chromosomes, excluding Robertsonian translocations. Hum Genet 1980; 54:365-70. [PMID: 6156888 DOI: 10.1007/bf00291584] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The silver-staining technique was used to study even cases of structural anomalies involving acrocentric chromosomes, excluding Robertsonian translocations. This technique allows identification of breakpoints and furnishes some information about interphase cell dynamics not seen on conventional chromosome preparations.
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49
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Abstract
A male child with Prader Willi syndrome and a de novo 9p/15q translocation is described. A review of the literature showed that a translocation involving 15q has been described in seven cases of this syndrome. The possible relationship between Prader Willi syndrome and breakage of chromosome no. 15 in qll region is discussed.
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50
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Michaelsen KF, Lundsteen C, Hansen FJ. Prader-Willi syndrome and chromosomal mosaicism 46,XY/47,XY,+mar in two cases. Clin Genet 1979; 16:147-50. [PMID: 573673 DOI: 10.1111/j.1399-0004.1979.tb00983.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Two cases of the Prader-Willi syndrome with 46,XY/47,XY,+mar are reported. The majority of Prader-Willi patients with chromosome abnormalities have either 15/15 translocations or mosaicism. Both of these aberrations presumably occur after fertilization. A possible relationship between high parental age and chromosome abnormalities in the Prader-Willi syndrome is discussed.
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