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1.
Hum Genet ; 138(10): 1183-1200, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31471722

RESUMO

The glutamate pyruvate transaminase 2 (GPT2) gene produces a nuclear-encoded mitochondrial enzyme that catalyzes the reversible transfer of an amino group from glutamate to pyruvate, generating alanine and alpha-ketoglutarate. Recessive mutations in GPT2 have been recently identified in a new syndrome involving intellectual and developmental disability (IDD), postnatal microcephaly, and spastic paraplegia. We have identified additional families with recessive GPT2 mutations and expanded the phenotype to include small stature. GPT2 loss-of-function mutations were identified in four families, nine patients total, including: a homozygous mutation in one child [c.775T>C (p.C259R)]; compound heterozygous mutations in two siblings [c.812A>C (p.N271T)/c.1432_1433delGT (p.V478Rfs*73)]; a novel homozygous, putative splicing mutation [c.1035C>T (p.G345=)]; and finally, a recurrent mutation, previously identified in a distinct family [c.1210C>T (p.R404*)]. All patients were diagnosed with IDD. A majority of patients had remarkably small stature throughout development, many < 1st percentile for height and weight. Given the potential biological function of GPT2 in cellular growth, this phenotype is strongly suggestive of a newly identified clinical susceptibility. Further, homozygous GPT2 mutations manifested in at least 2 of 176 families with IDD (approximately 1.1%) in a Pakistani cohort, thereby representing a relatively common cause of recessive IDD in this population, with recurrence of the p.R404* mutation in this population. Based on variants in the ExAC database, we estimated that approximately 1 in 248 individuals are carriers of moderately or severely deleterious variants in GPT2.


Assuntos
Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/genética , Genes Recessivos , Predisposição Genética para Doença , Mutação , Fenótipo , Transaminases/genética , Adolescente , Alelos , Substituição de Aminoácidos , Deficiências do Desenvolvimento/metabolismo , Ativação Enzimática , Éxons , Feminino , Frequência do Gene , Estudos de Associação Genética , Genética Populacional , Genótipo , Humanos , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Imagem por Ressonância Magnética , Masculino , Mitocôndrias/genética , Mitocôndrias/metabolismo , Modelos Moleculares , Linhagem , Conformação Proteica , Sítios de Splice de RNA , Análise de Sequência de DNA , Relação Estrutura-Atividade , Transaminases/química , Transaminases/metabolismo
2.
Genet Sel Evol ; 51(1): 36, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31382878

RESUMO

BACKGROUND: Recessive loss-of-function (LOF) alleles at genes which are essential for life, can result in early embryonic mortality. Cattle producers can use the LOF carrier status of individual animals to make selection and mate allocation decisions. METHODS: Two beef cattle breeding strategies i.e. (1) selection against LOF carriers as parents and (2) simultaneous selection and mate allocation to avoid the occurrence of homozygous offspring in three scenarios, which differed in number and frequency of LOF alleles were evaluated using the mate selection program, MateSel. Scenarios included (a) seven loci with high-frequency LOF alleles, (b) 76 loci with low-frequency LOF alleles, and (c) 50 loci with random high- and low-frequency LOF alleles. In addition, any savings resulting from the information obtained by varying the percentage (0-100%) of the herd genotyped, together with segregation analysis to cover ungenotyped animals, were calculated to determine (1) which percentage optimized net profit for a fixed cost of genotyping ($30/test), and (2) the breakeven cost for genotyping. RESULTS: With full knowledge of the LOF alleles carried by selection candidates, the most profitable breeding strategy was always simultaneous selection and mate allocation to avoid homozygous affected offspring (aa) as compared to indiscriminate selection against carrier parents (Aa). The breakeven value of genotyping depended on the number of loci modeled, the LOF allele frequencies, and the mating/selection strategies used. Genotyping was most valuable when it was used to avoid otherwise high levels of embryonic mortalities. As the number of essential loci with LOF alleles increased, especially when some were present at relatively high minor allele frequencies, embryonic losses increased, and profit was maximized by genotyping 10 to 20% of a herd and using that information to reduce these losses. CONCLUSIONS: Genotyping 100% of the herd was never the most profitable outcome in any scenario; however, genotyping some proportion of the herd, together with segregation analysis to cover ungenotyped animals, maximized overall profit in scenarios with large numbers of loci with LOF alleles. As more LOF alleles are identified, such a mate selection software will likely be required to optimally select and allocate matings to balance the rate of genetic gain, embryonic losses, and inbreeding.


Assuntos
Cruzamento , Bovinos/genética , Genes Recessivos , Software , Alelos , Animais , Feminino , Fertilidade , Técnicas de Genotipagem/veterinária , Mutação com Perda de Função , Masculino , Seleção Genética
3.
Plant Mol Biol ; 100(6): 647-658, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31154655

RESUMO

KEY MESSAGE: Found a trans-splicing of PHYTOENE SYNTHASE 1 alters tomato fruit color by map-based cloning, functional complementation and RACE providing an insight into fruit color development. Color is an important fruit quality trait and a major determinant of the economic value of tomato (Solanum lycopersicum). Fruit color inheritance in a yellow-fruited cherry tomato (cv. No. 22), named yellow-fruited tomato 2 (yft2), was shown to be controlled by a single recessive gene, YFT2. The YFT2 gene was mapped in a 95.7 kb region on chromosome 3, and the candidate gene, PHYTOENE SYNTHASE 1 (PSY1), was confirmed by functional complementation analysis. Constitutive over expression of PSY1 in yft2 increased the accumulation of carotenoids and resulted in a red fruit color, while no causal mutation was detected in the YFT2 allele of yft2, compared with red-fruited SL1995 cherry tomato or cultivated variety (cv. M82). Expression of YFT2 3' region in yft2 was significantly lower than in SL1995, and further studies revealed a difference in YFT2 post-transcriptional processing in yft2 compared with SL1995 and cv. M82, resulting in a longer YFT2 transcript. The alternatively trans-spliced allele of YFT2 in yft2 is predicted to encode a novel LT-YFT2 protein of 432 amino acid (AA) residues, compared to the 412 AA YFT2 protein of SL1995. The trans-spliced event also resulted in significantly down regulated expression of YFT2 in yft2 tomato, and the YFT2 allele suppressed expression of the downstream genes involved in the carotenoid biosynthesis pathway and carotenoids synthesis by a mechanism of the feed-forward regulation. In conclusion, we found that trans-splicing of YFT2 alters tomato fruit color, providing new insights into fruit color development.


Assuntos
Lycopersicon esculentum/metabolismo , Pigmentação/genética , Proteínas de Plantas/metabolismo , Processamento Alternativo , Carotenoides/metabolismo , Mapeamento Cromossômico , Clonagem Molecular , Cor , DNA Complementar/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genes Recessivos , Teste de Complementação Genética , Genótipo , Lycopersicon esculentum/genética , Mutação , Proteínas de Plantas/genética , Trans-Splicing
4.
Hum Genet ; 138(10): 1071-1075, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31175426

RESUMO

While the importance of tight junctions in hearing is well established, the role of Claudin- 9 (CLDN9), a tight junction protein, in human hearing and deafness has not been explored. Through whole-genome sequencing, we identified a one base pair deletion (c.86delT) in CLDN9 in a consanguineous family from Turkey with autosomal recessive nonsyndromic hearing loss. Three affected members of the family had sensorineural hearing loss (SNHL) ranging from moderate to profound in severity. The variant is predicted to cause a frameshift and produce a truncated protein (p.Leu29ArgfsTer4) in this single-exon gene. It is absent in public databases as well as in over 1000 Turkish individuals, and co-segregates with SNHL in the family. Our in vitro studies demonstrate that the mutant protein does not localize to cell membrane as demonstrated for the wild-type protein. Mice-lacking Cldn9 have been shown to develop SNHL. We conclude that CLDN9 is essential for proper audition in humans and its disruption leads to SNHL in humans.


Assuntos
Claudinas/genética , Surdez/diagnóstico , Surdez/genética , Genes Recessivos , Estudos de Associação Genética , Predisposição Genética para Doença , Variação Genética , Claudinas/química , Claudinas/metabolismo , Biologia Computacional/métodos , Análise Mutacional de DNA , Feminino , Mutação da Fase de Leitura , Humanos , Mutação , Linhagem , Polimorfismo Genético , Transporte Proteico , Turquia , Sequenciamento Completo do Genoma
5.
Hum Genet ; 138(10): 1117-1122, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31243543

RESUMO

The Israeli population mainly includes Jews, Muslim and Christian Arabs, and Druze. Data on genetic diseases present in the population have been systematically collected and are available online in the Israeli national genetic database. Among the Israeli Arabs in December 31 2018, the database included molecular data on six diseases relatively frequent in the whole population: thalassemia, familial Mediterranean fever (FMF), cystic fibrosis, deafness, phenylketonuria or congenital adrenal hyperplasia as well as data on 632 autosomal recessive diseases among Muslim Israeli Arabs, 52 among the Christian Arabs and 79 among Druze. A single variant was characterized in 590 out of the 771 genes causing disorders in which the molecular basis was known. Many of the variants reported among Arabs in Israel are novels, most being found in one community only. Some variants are ancient and for instance, consistent with the migration history, several variants are found in the Bedouins from the Negev as well as from the Arab peninsula. In the 181 other disorders more than one variant was characterized either in the same gene or in more than one gene. While it is probable that most of these cases represent random events in some cases the reason may be a selective advantage to the heterozygotes.


Assuntos
Árabes/genética , Genes Recessivos , Doenças Genéticas Inatas/epidemiologia , Doenças Genéticas Inatas/genética , Predisposição Genética para Doença , Doenças Genéticas Inatas/diagnóstico , Variação Genética , Heterozigoto , Humanos , Israel/epidemiologia , Programas de Rastreamento , Vigilância da População
6.
Genet Test Mol Biomarkers ; 23(6): 428-432, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31081706

RESUMO

Background: Autosomal recessive congenital ichthyoses (ARCI) are a group of rare nonsyndromic genodermatoses characterized by generalized scaly appearance of the epidermis with markedly impaired cutaneous barriers owing to defects in keratinization related genes. In this study, we ascertained a consanguineous Pakistani family affected with ARCI. Aims: To investigate genetic defect underlying disease phenotype in the affected family. Methods: All available members of the family (affected and unaffected) were sampled. Whole exome sequencing (WES) was performed on DNA of the proband and the data were analyzed for probable pathogenic variants. Segregation of the identified variant was validated by Sanger sequencing. Results: Analysis of the WES data identified a novel nonsense mutation, c.762C>G, in the PNPLA1 (patatin-like phospholipase domain containing 1) gene. The protein product of of this gene is involved in lipid organization during cornified cell envelope formation. The variant is predicted to result in the generation of a premature truncation site at amino acid position 254 (p.Tyr254*). This would result in the loss of a large C-terminal portion of the protein suggesting it to be rendered nonfunctional. In silico protein structure modeling confirmed a detrimental effect of the variation on protein structure. Conclusions: The study supports the evidence for the prevalence of PNPLA1 mutations in distant ethnic groups. Despite the significant number of reported ARCI cases with PNPLA1 variants, a straightforward genotype-phenotype correlation cannot be established.


Assuntos
Ictiose Lamelar/genética , Lipase/genética , Adulto , Idoso , Códon sem Sentido/genética , Grupos Étnicos/genética , Família , Feminino , Genes Recessivos/genética , Humanos , Ictiose Lamelar/metabolismo , Lipase/fisiologia , Masculino , Pessoa de Meia-Idade , Mutação/genética , Paquistão , Linhagem , Fenótipo , Sequenciamento Completo do Exoma/métodos
7.
Hum Genet ; 138(6): 673-679, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31069506

RESUMO

The study of Mendelian diseases and the identification of their causative genes are of great significance in the field of genetics. The evaluation of the pathogenicity of genes and the total number of Mendelian disease genes are both important questions worth studying. However, very few studies have addressed these issues to date, so we attempt to answer them in this study. We calculated the gene pathogenicity prediction (GPP) score by a machine learning approach (random forest algorithm) to evaluate the pathogenicity of genes. When we applied the GPP score to the testing gene set, we obtained an accuracy of 80%, recall of 93% and area under the curve of 0.87. Our results estimated that a total of 10,384 protein-coding genes were Mendelian disease genes. Furthermore, we found the GPP score was positively correlated with the severity of disease. Our results indicate that GPP score may provide a robust and reliable guideline to predict the pathogenicity of protein-coding genes. To our knowledge, this is the first trial to estimate the total number of Mendelian disease genes.


Assuntos
Algoritmos , Doenças Genéticas Inatas/genética , Predisposição Genética para Doença/genética , Aprendizado de Máquina , Genes Dominantes/genética , Genes Recessivos/genética , Doenças Genéticas Inatas/diagnóstico , Humanos , Curva ROC
8.
BMC Med Genet ; 20(1): 80, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088393

RESUMO

BACKGROUND: Intellectual disability/developmental delay is a complex condition with extraordinary heterogeneity. A large proportion of patients lacks a specific diagnosis. Next generation sequencing, enabling identification of genetic variations in multiple genes, has become an efficient strategy for genetic analysis in intellectual disability/developmental delay. METHODS: Clinical data of 112 Chinese families with unexplained intellectual disability/developmental delay was collected. Targeted next generation sequencing of 454 genes related to intellectual disability/developmental delay was performed for all 112 index patients. Patients with promising variants and their other family members underwent Sanger sequencing to validate the authenticity and segregation of the variants. RESULTS: Fourteen promising variants in genes EFNB1, MECP2, ATRX, NAA10, ANKRD11, DHCR7, LAMA1, NFIX, UBE3A, ARID1B and PTPRD were identified in 11 of 112 patients (11/112, 9.82%). Of 14 variants, eight arose de novo, and 13 are novel. Nine patients (9/112, 8.03%) got definite molecular diagnoses. It is the first time to report variants in EFNB1, NAA10, DHCR7, LAMA1 and NFIX in Chinese intellectual disability/developmental delay patients and first report about variants in NAA10 and LAMA1 in affected individuals of Asian ancestry. CONCLUSIONS: Targeted next generation sequencing of 454 genes is an effective test strategy for patients with unexplained intellectual disability/developmental delay. Genetic heterogenicity is significant in this Chinese cohort and de novo variants play an important role in the diagnosis. Findings of this study further delineate the corresponding phenotypes, expand the mutation spectrum and support the involvement of PTPRD in the disease.


Assuntos
Deficiências do Desenvolvimento/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Deficiência Intelectual/genética , Mutação , Adolescente , Criança , Pré-Escolar , China , Cromossomos Humanos X , Feminino , Genes Dominantes , Genes Recessivos , Heterogeneidade Genética , Humanos , Lactente , Masculino , Linhagem , Fenótipo
9.
Gene ; 709: 65-74, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31129248

RESUMO

BACKGROUND: Autosomal recessive non-syndromic hearing loss (ARNSHL) is a highly heterogeneous genetic disease. PDZD7 is a new ARNSHL associated gene. Until now, nine PDZD7 biallelic mutation families with ARNSHL have been reported. Here we report a case of Chinese patient with ARNSHL linked to novel mutations in PDZD7 genes. METHOD: The pathogenic mutations were detected by whole exome sequencing for hereditary deafness-related genes of both the proband and his parents. We used kinship detection, mutational hazard prediction, genotype-phenotype correlation analysis and variation screening for potential pathogenic mutations. Re-sequencing was used to confirm the mutations by Sanger sequence. Real time quantitative PCR (RT-qPCR) was used to analyze the PDZD7 gene expression. Population-based screening for variation frequency, evolutionary conservation comparisons, pathogenicity evaluation, and protein structure prediction were conducted to assess the pathogenicity of the novel mutations of PDZD7 gene. RESULTS: We determined three variants of the PDZD7 gene that contributed to the deafness of the patient (PDZD7 c.192G > A, p. Met64Ile; c.1648C > T p. Gln550* and c.2341_2352delCGCAGCCGCAGCp. Arg781_Ser 784del). Pathogenic analysis in accordance with the ACMG/AMP Standards and Guidelines identified two novel mutations as Likely Pathogenic. The expression level of PDZD7 gene in the patient was decreased compared to the normal control (P < 0.001). CONCLUSION: Three mutations in PDZD7 gene linked to ARNSHL were identified in a Chinese pedigree. The findings expand not only our knowledge of genetic causes of ARNSHL, but also PDZD7 genes mutation spectrum of the disease. They will aid personalized genetic counseling, molecular diagnostics and clinical management of this condition.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Proteínas de Transporte/genética , Genes Recessivos , Perda Auditiva/genética , Mutação , Grupo com Ancestrais do Continente Asiático/estatística & dados numéricos , Criança , Surdez/genética , Família , Estudos de Associação Genética , Predisposição Genética para Doença , Perda Auditiva/etnologia , Heterozigoto , Humanos , Masculino , Linhagem
10.
Mol Med Rep ; 19(6): 4711-4718, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31059048

RESUMO

Autosomal recessive cornea plana is a very rare hereditary ocular disease, characterized by a flattened corneal curvature, marked hyperopia due to low refractive power and frequently consequent accommodative esotropia. Other features include various cornea anterior segment abnormalities, without systemic problems. The purpose of the present study was to investigate the clinical and molecular alterations in a Chinese family with cornea plana. Full ophthalmic examinations of the patients were performed, including slit­lamp examination, fundus examination and ocular ultrasound. Whole­exome sequencing data were screened for pathological variants in the proband, which were confirmed by Sanger sequencing. One novel missense mutation, c.242A>G (p.N81S) and another novel 7 base­pair deletion mutation, c.772­779del (p.G258Cfs*30), were detected in the keratocan (KERA) gene; two affected siblings inherited these variations in a compound heterozygous state, which were derived from the clinically unaffected heterozygous father (c.772_779del) and mother (c.242A>G), respectively. Neither mutation was observed in unrelated healthy controls (n=200). Multiple computer software predictions supported the pathogenicity of the two variants. Furthermore, protein modeling prediction was performed to better understand the molecular basis of cornea plana, particularly the importance of the leucine­rich repeat domain. This study presents the 14th pathogenic KERA mutations identified worldwide and the first in East Asia so far, to the best of our knowledge. These findings guided prenatal diagnosis for the family in question and expand on the variant spectrum of KERA, therefore facilitating genetic counseling.


Assuntos
Doenças da Córnea/genética , Genes Recessivos/genética , Proteoglicanas/genética , Grupo com Ancestrais do Continente Asiático , Sequência de Bases , China , Córnea/anormalidades , Córnea/patologia , Doenças da Córnea/diagnóstico , Doenças da Córnea/patologia , Distrofias Hereditárias da Córnea/diagnóstico , Distrofias Hereditárias da Córnea/genética , Análise Mutacional de DNA , Éxons/genética , Anormalidades do Olho/genética , Anormalidades do Olho/patologia , Feminino , Humanos , Mutação de Sentido Incorreto , Linhagem , Análise de Sequência , Deleção de Sequência , Sequenciamento Completo do Exoma
11.
BMC Plant Biol ; 19(1): 157, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31023214

RESUMO

BACKGROUND: Pedicel orientation can affect the female flower orientation and seed yield in cucumber. A spontaneous mutant possessing upward growth of pedicels was identified in the wild type inbred strain 9930 and named upward-pedicel (up). The morphological and genetic analyses of up were performed in this study. In order to clone the up gene, 933 F2 individuals and 524 BC1 individuals derived from C-8-6 (WT) and up were used for map-based cloning. RESULTS: up was mapped to a 35.2 kb physical interval on chromosome 1, which contains three predicted genes. Sequencing analysis revealed that a 5-bp deletion was found in the second exon of Csa1G535800, and it led to a frameshift mutation resulting in a premature stop codon. The candidate gene of CsUp (Csa1G535800) was further confirmed via genomic and cDNA sequencing in biparental and natural cucumber populations. Sequencing data showed that a 4-bp deletion was found in the sixth exon of Csa1G535800 in CGN19839, another inbred line, and there was also a mutation of an amino acid in Csa1G535800 that could contribute to the upward growth of pedicels in CGN19839. Moreover, it was found that Csa1G535800 exhibited strong expression in the pedicel of WT, suggesting its important role in development of pedicel orientation. Thus, Csa1G535800 was considered to be the candidate gene of CsUp. CONCLUSIONS: CsUp encodes an Auxilin-like protein and controls pedicel orientation in cucumber. The identification of CsUp may help us to understand the mechanism of pedicel orientation development and allow for investigation of novel functions of Auxilin-like proteins in cucumber.


Assuntos
Auxilinas/genética , Mapeamento Cromossômico , Cucumis sativus/genética , Genes de Plantas , Estudos de Associação Genética , Mutação/genética , Sequência de Aminoácidos , Sequência de Bases , Segregação de Cromossomos , Cromossomos de Plantas/genética , Cruzamentos Genéticos , Regulação da Expressão Gênica de Plantas , Genes Recessivos , Loci Gênicos , Fenótipo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Característica Quantitativa Herdável , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
12.
Nat Genet ; 51(5): 772-776, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30962618

RESUMO

In numerous applications, from working with animal models to mapping the genetic basis of human disease susceptibility, knowing whether a single disrupting mutation in a gene is likely to be deleterious is useful. With this goal in mind, a number of measures have been developed to identify genes in which protein-truncating variants (PTVs), or other types of mutations, are absent or kept at very low frequency in large population samples-genes that appear 'intolerant' to mutation. One measure in particular, the probability of being loss-of-function intolerant (pLI), has been widely adopted. This measure was designed to classify genes into three categories, null, recessive and haploinsufficient, on the basis of the contrast between observed and expected numbers of PTVs. Such population-genetic approaches can be useful in many applications. As we clarify, however, they reflect the strength of selection acting on heterozygotes and not dominance or haploinsufficiency.


Assuntos
Mutação , Animais , Frequência do Gene , Genes Recessivos , Deriva Genética , Genética Populacional , Haploinsuficiência , Heterozigoto , Humanos , Mutação com Perda de Função , Modelos Genéticos , Seleção Genética
13.
BMC Med Genet ; 20(1): 61, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30953456

RESUMO

BACKGROUND: Restrictive cardiomyopathy is a rare cardiac disease, for which several genes including TNNT2, MYPN, FLNC and TNNI3 have been associated with its familial form. CASE PRESENTATION: Here we describe a female proband with a severely manifested restrictive phenotype leading to heart transplantation at the age of 41, who was found homozygous for the novel TNNI3 mutation: NM_000363.4:c.586G > C, p.(Asp196His). Her parents were third-degree cousins originating from a small village and although they were found heterozygous for the same variant they displayed no symptoms of the disease. Her older sister who was also found heterozygous was asymptomatic. Her twin sister and her brother who were homozygous for the same variant displayed a restrictive and a hypertrophic phenotype, respectively. Their children are all carriers of the mutation and remain asymptomatic until the age of 21. CONCLUSION: These observations point to a recessive mode of inheritance reported for the first time for this combination of gene/disease.


Assuntos
Cardiomiopatias/genética , Genes Recessivos , Mutação , Troponina I/genética , Adulto , Feminino , Genótipo , Humanos , Masculino , Linhagem
14.
BMC Med Genet ; 20(1): 60, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30953472

RESUMO

BACKGROUND: MYO15A variants are responsible for human non-syndromic autosomal recessive deafness (DFNB3). The majority of MYO15A variants are associated with a congenital severe-to-profound hearing loss phenotype, except for MYO15A variants in exon 2, which cause a milder auditory phenotype, suggesting a genotype-phenotype correlation of MYO15A. However, MYO15A variants not in exon 2 related to a milder phenotype have also been reported, indicating that the genotype-phenotype correlation of MYO15A is complicated. This study aimed to provide more cases of MYO15A variation with diverse phenotypes to analyse this complex correlation. METHODS: Fifteen Chinese autosomal recessive non-syndromic hearing loss (ARNSHL) individuals with MYO15A variants (8 males and 7 females) from 14 unrelated families, identified by targeted gene capture of 127 known candidate deafness genes, were recruited. Additionally, we conducted a review of the literature to further analyses all reported MYO15A genotype-phenotype relationships worldwide. RESULTS: We identified 16 novel variants and 12 reported pathogenic MYO15A variants in 15 patients, two of which presented with a milder phenotype. Interestingly, one of these cases carried two reported pathogenic variants in exon 2, while the other carried two novel variants not in exon 2. Based on our literature review, MYO15A genotype-phenotype correlation analysis showed that almost all domains were reported to be correlated with a milder phenotype. However, variants in the N-terminal domain were more likely to cause a milder phenotype. Using next-generation sequencing (NGS), we also found that the number of known MYO15A variants with milder phenotypes in Southeast Asia has increased in recent years. CONCLUSION: Our work extended the MYO15A variant spectrum, enriched our knowledge of auditory phenotypes, and tried to explore the genotype-phenotype correlation in different populations in order to investigate the cause of the complex MYO15A genotype-phenotype correlation.


Assuntos
Genes Recessivos , Genótipo , Perda Auditiva/genética , Miosinas/genética , Fenótipo , Adolescente , Adulto , Pré-Escolar , China , Grupos Étnicos , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Adulto Jovem
15.
BMC Med Genet ; 20(1): 62, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30961538

RESUMO

BACKGROUND: Reports on autosomal recessive optic atrophy (arOA) are sparse and so far, only one gene has been specifically associated with non-syndromic arOA, namely TMEM126A. To date, all reports of pathogenic TMEM126A variants are from affected individuals of Maghrebian origin, who all carry an identical nonsense variant. Here we report two novel variants in the TMEM126A gene from non-Maghreb individuals, both found in affected individuals with an arOA phenotype. CASE PRESENTATION: We report three affected individuals from two families. The proband of family A, a 24-year-old Turkish woman, was diagnosed with visual loss in early childhood but a diagnosis of optic atrophy was only made at 14 years. A diagnostic gene panel revealed a splice donor variant (c.86 + 2 T > C) in homozygous state in the TMEM126A gene. Analysis of this variant based on RNA from whole blood revealed a single aberrant transcript lacking exon 2, presumably representing a functional null allele. Two siblings from family B, a 16-year old Iraqi girl and her 14-year old brother, were diagnosed with optic atrophy in early childhood. A missense variant p.(S36 L) in the TMEM126A gene was identified in homozygous state in a gene panel-based diagnostic setting in both siblings. This missense variant is ultra rare in the general population, affects a highly evolutionarily conserved amino acid and segregates with the disease within the family. The three probands reported in this study had a relatively mild clinical course without any evidence of a syndromic (e.g. neurological) comorbidity, which is in line with previous studies. CONCLUSIONS: We provide additional evidence for the implication of biallelic pathogenic TMEM126A variants in arOA. Our findings extend both the mutational spectrum and geographic presence of TMEM126A in arOA. Screening of the entire gene should be considered in affected individuals presenting with features resembling arOA and also from non-Maghrebian descent.


Assuntos
Genes Recessivos , Proteínas de Membrana/genética , Atrofia Óptica/genética , Adolescente , Códon sem Sentido , Feminino , Humanos , Masculino , Adulto Jovem
16.
Hum Genet ; 138(6): 593-600, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30982135

RESUMO

Postaxial polydactyly (PAP) is a common limb malformation that often leads to cosmetic and functional complications. Molecular evaluation of polydactyly can serve as a tool to elucidate genetic and signaling pathways that regulate limb development, specifically, the anterior-posterior specification of the limb. To date, only five genes have been identified for nonsyndromic PAP: FAM92A, GLI1, GLI3, IQCE and ZNF141. In this study, two Pakistani multiplex consanguineous families with autosomal recessive nonsyndromic PAP were clinically and molecularly evaluated. From both pedigrees, a DNA sample from an affected member underwent exome sequencing. In each family, we identified a segregating frameshift (c.591dupA [p.(Q198Tfs*21)]) and nonsense variant (c.2173A > T [p.(K725*)]) in KIAA0825 (also known as C5orf36). Although KIAA0825 encodes a protein of unknown function, it has been demonstrated that its murine ortholog is expressed during limb development. Our data contribute to the establishment of a catalog of genes important in limb patterning, which can aid in diagnosis and obtaining a better understanding of the biology of polydactyly.


Assuntos
Dedos/anormalidades , Genes Recessivos/genética , Predisposição Genética para Doença/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Mutação , Polidactilia/genética , Dedos do Pé/anormalidades , Animais , Consanguinidade , Saúde da Família , Feminino , Dedos/patologia , Genótipo , Humanos , Masculino , Camundongos Endogâmicos C57BL , Linhagem , Fenótipo , Polidactilia/patologia , Dedos do Pé/patologia , Sequenciamento Completo do Exoma/métodos
17.
Mol Vis ; 25: 155-164, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30820151

RESUMO

Purpose: To identify the genetic basis for retinitis pigmentosa (RP) in a cohort of Jewish patients from Caucasia. Methods: Patients underwent a detailed ophthalmic evaluation, including funduscopic examination, visual field testing, optical coherence tomography (OCT), and electrophysiological tests, electroretinography (ERG) and visual evoked potentials (VEP). Genetic analysis was performed with a combination of whole exome sequencing (WES) and Sanger sequencing. Bioinformatic analysis of the WES results was performed via a customized pipeline. Pathogenicity of the identified intronic variant was evaluated in silico using the web tool Human Splicing Finder, and in vitro, using a minigene-based splicing assay. Linkage disequilibrium (LD) analysis was used to demonstrate a founder effect, and the decay of LD over generations around the mutation in Caucasus Jewish chromosomes was modeled to estimate the age of the most recent common ancestor. Results: In eight patients with RP from six unrelated families, all of Caucasus Jewish ancestry, we identified a novel homozygous intronic variant, located at position -9 of PDE6B intron 15. The c.1921-9C>G variant was predicted to generate a novel acceptor splice site, nine bases upstream of the original splice site of intron 15. In vitro splicing assay demonstrated that this novel acceptor splice site is used instead of the wild-type site, leading to an 8-bp insertion into exon 16, which is predicted to cause a frameshift. The presence of a common ancestral haplotype in mutation-bearing chromosomes was compatible with a founder effect. Conclusions: The PDE6B c.1921-9C>G intronic mutation is a founder mutation that accounts for at least 40% (6/15 families) of autosomal recessive RP among Caucasus Jews. This result is highly important for molecular diagnosis, carrier screening, and genetic counseling in this population.


Assuntos
Nucleotídeo Cíclico Fosfodiesterase do Tipo 6/genética , Mutação da Fase de Leitura , Judeus , Sítios de Splice de RNA , Retinite Pigmentosa/genética , Adulto , Idoso , Biologia Computacional , Nucleotídeo Cíclico Fosfodiesterase do Tipo 6/deficiência , Eletrorretinografia , Potenciais Evocados Visuais/fisiologia , Éxons , Feminino , Efeito Fundador , Expressão Gênica , Genes Recessivos , Homozigoto , Humanos , Íntrons , Desequilíbrio de Ligação , Masculino , Pessoa de Meia-Idade , Retina/diagnóstico por imagem , Retina/metabolismo , Retina/patologia , Retinite Pigmentosa/diagnóstico por imagem , Retinite Pigmentosa/etnologia , Retinite Pigmentosa/patologia , Sibéria/etnologia , Tomografia de Coerência Óptica , Sequenciamento Completo do Exoma
18.
Gene ; 700: 65-69, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-30898718

RESUMO

INTRODUCTION: Adams-Oliver syndrome (AOS) is a rare developmental disorder characterized by the combination of aplasia cutis congenita of the scalp vertex and terminal transverse limb defects. DOCK6 (Dedicator of cytokinesis 6) is one of the six identified AOS genes. METHODS: We performed targeted next-generation sequencing (NGS) of a child with an AOS phenotype. Sanger DNA sequencing further validated her lineal consanguinity. To explore the pathological features of the mutation, a minigene assay was used to investigate the effects of the mutation on splicing. RESULTS: Two compound heterozygous DOCK6 mutations (c.4106+2T>C and c.3063 C>G (p.Y1021*)) were identified in this family, and both mutations have not been reported previously. Sanger DNA sequencing indicated that the mutations were inherited maternally and paternally, respectively. The results of the minigene assay showed that the c.4106+2T>C mutation resulted in aberrant splicing and caused a four-nucleotide insertion in the transcript and a premature stop codon. CONCLUSIONS: Our findings expanded the number of reported cases of this rare disease and the mutation spectrum of DOCK6 mutations, which can serve as the basis for prenatal diagnosis and genetic counseling.


Assuntos
Displasia Ectodérmica/genética , Fatores de Troca do Nucleotídeo Guanina/genética , Deformidades Congênitas dos Membros/genética , Mutação , Dermatoses do Couro Cabeludo/congênito , Análise de Sequência de DNA/métodos , Pré-Escolar , Consanguinidade , Feminino , Genes Recessivos , Heterozigoto , Humanos , Masculino , Linhagem , Fenótipo , Dermatoses do Couro Cabeludo/genética
19.
PLoS Genet ; 15(3): e1008055, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30875370

RESUMO

Lethal recessive alleles cause pre- or postnatal death in homozygous affected individuals, reducing fertility. Especially in small size domestic and wild populations, those alleles might be exposed by inbreeding, caused by matings between related parents that inherited the same recessive lethal allele from a common ancestor. In this study we report five relatively common (up to 13.4% carrier frequency) recessive lethal haplotypes in two commercial pig populations. The lethal haplotypes have a large effect on carrier-by-carrier matings, decreasing litter sizes by 15.1 to 21.6%. The causal mutations are of different type including two splice-site variants (affecting POLR1B and TADA2A genes), one frameshift (URB1), and one missense (PNKP) variant, resulting in a complete loss-of-function of these essential genes. The recessive lethal alleles affect up to 2.9% of the litters within a single population and are responsible for the death of 0.52% of the total population of embryos. Moreover, we provide compelling evidence that the identified embryonic lethal alleles contribute to the observed heterosis effect for fertility (i.e. larger litters in crossbred offspring). Together, this work marks specific recessive lethal variation describing its functional consequences at the molecular, phenotypic, and population level, providing a unique model to better understand fertility and heterosis in livestock.


Assuntos
Genes Letais , Mutação com Perda de Função , Sus scrofa/embriologia , Sus scrofa/genética , Sequência de Aminoácidos , Animais , Feminino , Fertilidade/genética , Genes Recessivos , Deriva Genética , Genética Populacional , Haplótipos , Vigor Híbrido/genética , Hibridização Genética/genética , Tamanho da Ninhada de Vivíparos/genética , Masculino , Gravidez , RNA Polimerase I/genética , Análise de Sequência de RNA , Sequenciamento Completo do Genoma
20.
PLoS Genet ; 15(3): e1007873, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30889179

RESUMO

Autosomal recessive retinal degenerative diseases cause visual impairment and blindness in both humans and dogs. Currently, no standard treatment is available, but pioneering gene therapy-based canine models have been instrumental for clinical trials in humans. To study a novel form of retinal degeneration in Labrador retriever dogs with clinical signs indicating cone and rod degeneration, we used whole-genome sequencing of an affected sib-pair and their unaffected parents. A frameshift insertion in the ATP binding cassette subfamily A member 4 (ABCA4) gene (c.4176insC), leading to a premature stop codon in exon 28 (p.F1393Lfs*1395), was identified. In contrast to unaffected dogs, no full-length ABCA4 protein was detected in the retina of an affected dog. The ABCA4 gene encodes a membrane transporter protein localized in the outer segments of rod and cone photoreceptors. In humans, the ABCA4 gene is associated with Stargardt disease (STGD), an autosomal recessive retinal degeneration leading to central visual impairment. A hallmark of STGD is the accumulation of lipofuscin deposits in the retinal pigment epithelium (RPE). The discovery of a canine homozygous ABCA4 loss-of-function mutation may advance the development of dog as a large animal model for human STGD.


Assuntos
Membro 4 da Subfamília A de Transportadores de Cassetes de Ligação de ATP/genética , Doenças do Cão/genética , Degeneração Macular/congênito , Mutação , Membro 4 da Subfamília A de Transportadores de Cassetes de Ligação de ATP/química , Membro 4 da Subfamília A de Transportadores de Cassetes de Ligação de ATP/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Códon sem Sentido , Modelos Animais de Doenças , Doenças do Cão/metabolismo , Doenças do Cão/patologia , Cães , Feminino , Genes Recessivos , Homozigoto , Humanos , Lipofuscina/metabolismo , Degeneração Macular/genética , Degeneração Macular/metabolismo , Degeneração Macular/veterinária , Masculino , Microscopia de Fluorescência , Modelos Moleculares , Mutagênese Insercional , Linhagem , Conformação Proteica , Retina/metabolismo , Retina/patologia , Sequenciamento Completo do Genoma
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