Autosomal-dominant adult neuronal ceroid lipofuscinosis caused by duplication in DNAJC5 initially missed by Sanger and whole-exome sequencing

AbstractPontine autosomal dominant microangiopathy and leukoencephalopathy (PADMAL) is a rare hereditary cerebral small vessel disease. We report a novel collagen type IV alpha 1 (COL4A1) gene mutation in a Chinese family with PADMAL. The index case was followed up for 6 years. Neuroimaging, whole-exome sequencing, skin biopsy, and pedigree analysis were performed. She initially presented with minor head injury at age 38. MRI brain showed chronic lacunar infarcts in the pons, left thalamus, and right centrum semiovale. Extensive workup was unremarkable except for a patent foramen ovale (PFO). Despite anticoagulation, PFO closure, and antiplatelet therapy, the patient had recurrent lacunar infarcts in the pons and deep white matter, as well as subcortical microhemorrhages. Whole-exome sequencing demonstrated a novel c.*34G > T mutation in the 3′ untranslated region of COL4A1 gene. Skin biopsy subsequently demonstrated thickening of vascular basement membrane, proliferation of endothelial cells, and stenosis of vascular lumen. Three additional family members had gene testing and 2 of them were found to have the same heterozygous mutation. Of the 18 individuals in the pedigree of 3 generations, 12 had clinical and MRI evidence of PADMAL. The mechanisms of both ischemic and hemorrhagic stroke are likely the overexpression of COLT4A1 in the basement membrane and frugality of the vessel walls. Our findings suggest that the novel c.*34G > T mutation appears to have the same functional consequences as the previously reported COL4A1 gene mutations in patients with PADMAL and multi-infarct dementia of Swedish type.

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Identification of a novel pathogenic missense mutation in PRPF31 using whole exome sequencing: a case report

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2017-311405 ◽

2018 ◽

Vol 103 (6) ◽

pp. 761-767 ◽

Cited By ~ 2

Author(s):

Laura Bryant ◽

Olga Lozynska ◽

Anson Marsh ◽

Tyler E Papp ◽

Lucas van Gorder ◽

...

Keyword(s):

Exome Sequencing ◽

Missense Mutation ◽

Whole Exome Sequencing ◽

Protein Trafficking ◽

Protein Misfolding ◽

Autosomal Dominant ◽

Null Alleles ◽

Incomplete Penetrance ◽

Missense Mutations ◽

Whole Exome

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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Whole exome sequencing identified a second pathogenic variant in HOMER2 for autosomal dominant non-syndromic deafness

Clinical Genetics ◽

10.1111/cge.13422 ◽

2018 ◽

Vol 94 (5) ◽

pp. 419-428 ◽

Cited By ~ 3

Author(s):

X. Lu ◽

Q. Wang ◽

H. Gu ◽

X. Zhang ◽

Y. Qi ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Autosomal Dominant ◽

Pathogenic Variant ◽

Whole Exome

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Clinical and Molecular Characterization of Qatari Patients with Inherited Dysfibrinogenemia

Blood ◽

10.1182/blood-2021-149446 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1037-1037

Author(s):

Amna Gameil ◽

Hajer Al-Mulla ◽

Aliaa Amer ◽

Tawfeg Ben-Omran ◽

Mohamed A Yassin ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Autosomal Dominant ◽

Clinical Phenotype ◽

Pathogenic Mutation ◽

Functional Assay ◽

Sequencing Analysis ◽

Thrombin Time ◽

Whole Exome ◽

Antigen Assay

Abstract Background and Objectives: Inherited Dysfibrinogenemia is a rare functional fibrinogen disorder in which the fibrinogen protein is present but with a reduced function. Fibrinogen is a 340-kDa glycoprotein that is encoded by three genes namely: Fibrinogen Bb (FGB), Aa (FGA), and g (FGG). The disorder is characterized by a wide spectrum of clinical phenotypes, ranging from asymptomatic to mild- to-severe bleeding or thrombotic manifestations and recurrent miscarriages. The mode of inheritance is mostly autosomal dominant manner and frequently as a result of a point mutation in FGA (Arg35) and FGG (Arg301). The laboratory diagnosis is based on discrepancy between fibrinogen antigen (detected by immunoassay or by immuno-turbidimetric assay) and functional assay (detected by Clauss method or other clot-based assays). The disorder is often associated with prolonged activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT).Fibrinogen activity is reduced by Clauss method while the antigen assay remains normal. The management is directed towards prevention of bleeding with prophylactic fibrinogen concentrates or cryoprecipitate prior to invasive procedures, surgeries or delivery. Dysfibrinogenemia is a rare disorder yet it is very prevalent in Qatar as a result of high rate of consanguineous marriages. The aim of our study is to describe the clinical phenotype in relation to genotype in this cohort. Methods We conducted a retrospective analysis of 23 patients with Inherited Dysfibrinogenemia reported by our center from 2015 to 2020 . Patients with a positive family of history fibrinogen disorder and abnormal coagulation screen, low functional fibrinogen assay (by Clauss method) or normal antigen level by turbidimetry were included. Whole exome sequencing (WES) was performed on the proband case which detected a likely pathogenic mutation that was tested on subsequent cases. We diagnosed our patients with Inherited Dysfibrinogenemia based on both coagulation-based assays and molecular tests. Probable Inherited Dysfibrinogenemia was considered in patients where the molecular test or antigen assay were not performed. To assess the clinical phenotype, data was collected that included; age at diagnosis, gender, bleeding and thrombotic events as well as coagulation screening. (Table 1) Results 23 patients who were described in this cohort belong to the same tribe. 74% (17 o/23) were female and only 41% (7/17) reported an obstetric bleeding (postpartum or post abortion) and one reported mild bleeding that occurred in the postmenopausal period and no previous bleeding (case#19). The median age of diagnosis was 28.8 years (5-69) for the females. All male cases in the cohort were detected either during routine screening or prior to surgery with no previous history of bleeding. No thrombotic events were observed in this cohort. Genetic Analysis Following proper genetic counseling and informed consent, whole exome sequencing analysis (WES) was performed on the index case which included testing of the fibrinogen genes FGA, FGB and FGG. WES revealed a likely pathogenic mutation in the FGA gene (p. Arg35His (R35H) (CGT>CAT): c.104 G>A in exon 2)-Located within the cleavage site of fibrinopeptide A by thrombin (The UniProt Consortium, 2017), which is a mutational hotspot. This result is likely consistent with the diagnosis of Dysfibrinogenemia. Conclusion The FGA R35H mutation is considered a probable recurrent variant in a large tribe in the Qatari population and is associated with late onset mild bleeding manifestations in minority of cases . Despite the fact that the reported tribe is highly consanguineous, the R35H mutation behaved in an autosomal dominant manner rather than recessive in this cohort.Further studies to assess phenotype - genotype correlation of Dysfibrinogenemia is warranted. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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