Homozygosity mapping coupled with whole-exome sequencing and protein modelling identified a novel missense mutation in GUCY2D in a consanguineous Pakistani family with Leber congenital amaurosis

BackgroundVariants in PRPF31, which encodes pre-mRNA processing factor 31 homolog, are known to cause autosomal-dominant retinitis pigmentosa (adRP) with incomplete penetrance. However, the majority of mutations cause null alleles, with only two proven pathogenic missense mutations. We identified a novel missense mutation in PRPF31 in a family with adRP.MethodsWe performed whole exome sequencing to identify possible pathogenic mutations in the proband of a family with adRP. Available affected family members had a full ophthalmological evaluation including kinetic and two-colour dark adapted static perimetry, electroretinography and multimodal imaging of the retina. Two patients had evaluations covering nearly 20 years. We carried out segregation analysis of the probable mutation, PRPF31 c.590T>C. We evaluated the cellular localisation of the PRPF31 variant (p.Leu197Pro) compared with the wildtype PRPF31 protein.ResultsPRPF31 c.590T>C segregated with the disease in this four-generation autosomal dominant pedigree. There was intrafamilial variability in disease severity. Nyctalopia and mid-peripheral scotomas presented from the second to the fourth decade of life. There was severe rod >cone dysfunction. Visual acuity (VA) was relatively intact and was maintained until later in life, although with marked interocular asymmetries. Laboratory studies showed that the mutant PRPF31 protein (p.Leu197Pro) does not localise to the nucleus, unlike the wildtype PRPF31 protein. Instead, mutant protein resulted in punctate localisation to the cytoplasm.Conclusionsc.590T>C is a novel pathogenic variant in PRPF31 causing adRP with incomplete penetrance. Disease may be due to protein misfolding and associated abnormal protein trafficking to the nucleus.

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Exome sequencing identified a novelde novo OPA1mutation in a consanguineous family presenting with optic atrophy

Genetics Research ◽

10.1017/s0016672316000070 ◽

2016 ◽

Vol 98 ◽

Cited By ~ 2

Author(s):

LIOR COHEN ◽

SHAY TZUR ◽

NITZA GOLDENBERG-COHEN ◽

CONCETTA BORMANS ◽

DORON M. BEHAR ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Optic Neuropathy ◽

Optic Atrophy ◽

De Novo ◽

Extended Family ◽

Homozygosity Mapping ◽

Visual Field Defects ◽

Whole Exome ◽

Hereditary Optic Neuropathy

SummaryInherited optic neuropathies are a heterogeneous group of disorders characterized by mild to severe visual loss, colour vision deficit, central or paracentral visual field defects and optic disc pallor. Optic atrophies can be classified into isolated or non-syndromic and syndromic forms. While multiple modes of inheritance have been reported, autosomal dominant optic atrophy and mitochondrial inherited Leber's hereditary optic neuropathy are the most common forms. Optic atrophy type 1, caused by mutations in theOPA1gene is believed to be the most common hereditary optic neuropathy, and most patients inherit a mutation from an affected parent. In this study we used whole-exome sequencing to investigate the genetic aetiology in a patient affected with isolated optic atrophy. Since the proband was the only affected individual in his extended family, and was a product of consanguineous marriage, homozygosity mapping followed by whole-exome sequencing were pursued. Exome results identified a novelde novo OPA1mutation in the proband. We conclude, that thoughde novo OPA1mutations are uncommon, testing of common optic atrophy-associated genes such as mitochondrial mutations andOPA1gene sequencing should be performed first in single individuals presenting with optic neuropathy, even when dominant inheritance is not apparent.

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DMC1 mutation that causes human non-obstructive azoospermia and premature ovarian insufficiency identified by whole-exome sequencing

Journal of Medical Genetics ◽

10.1136/jmedgenet-2017-104992 ◽

2018 ◽

Vol 55 (3) ◽

pp. 198-204 ◽

Cited By ~ 24

Author(s):

Wen-Bin He ◽

Chao-Feng Tu ◽

Qiang Liu ◽

Lan-Lan Meng ◽

Shi-Min Yuan ◽

...

Keyword(s):

Exome Sequencing ◽

Missense Mutation ◽

Whole Exome Sequencing ◽

Male Patient ◽

Histological Analysis ◽

Pedigree Analysis ◽

Obstructive Azoospermia ◽

Ovarian Insufficiency ◽

Causative Gene ◽

Whole Exome

BackgroundThe genetic causes of the majority of male and female infertility caused by human non-obstructive azoospermia (NOA) and premature ovarian insufficiency (POI) with meiotic arrest are unknown.ObjectiveTo identify the genetic cause of NOA and POI in two affected members from a consanguineous Chinese family.MethodsWe performed whole-exome sequencing of DNA from both affected patients. The identified candidate causative gene was further verified by Sanger sequencing for pedigree analysis in this family. In silico analysis was performed to functionally characterise the mutation, and histological analysis was performed using the biopsied testicle sample from the male patient with NOA.ResultsWe identified a novel homozygous missense mutation (NM_007068.3: c.106G>A, p.Asp36Asn) in DMC1, which cosegregated with NOA and POI phenotypes in this family. The identified missense mutation resulted in the substitution of a conserved aspartic residue with asparaginate in the modified H3TH motif of DMC1. This substitution results in protein misfolding. Histological analysis demonstrated a lack of spermatozoa in the male patient’s seminiferous tubules. Immunohistochemistry using a testis biopsy sample from the male patient showed that spermatogenesis was blocked at the zygotene stage during meiotic prophase I.ConclusionsTo the best of our knowledge, this is the first report identifying DMC1 as the causative gene for human NOA and POI. Furthermore, our pedigree analysis shows an autosomal recessive mode of inheritance for NOA and POI caused by DMC1 in this family.

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