Epileptic Encephalopathy and Cerebellar Atrophy Resulting from Compound Heterozygous CACNA2D2 Variants

CACNA2D2 encodes an auxiliary subunit of the voltage-dependent calcium channel. To date, there have only been two reports of individuals with early-infantile epileptic encephalopathy due to CACNA2D2 mutations. In both reports, patients were homozygous for the identified variants. Here, we report a patient with epileptic encephalopathy and cerebellar atrophy who was found to have two novel variants in the CACNA2D2 gene: c.782C>T (p.Pro261Leu) and c.3137T>C (p.Leu1046Pro), by whole-exome sequencing. The variants were shown to be inherited in trans and the unaffected parents were confirmed to be heterozygous carriers. This is the third report of recessive CACNA2D2 variants associated with disease and the first report of compound heterozygous variants. The clinical description of this new case highlights the phenotypic similarities amongst individuals with CACNA2D2-related disease and suggests that CACNA2D2 should be considered as a differential diagnosis in individuals with cerebellar dysfunction and multiple seizure types that begin in the first year of life.

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Case Report: Novel Compound-Heterozygous Variants of SKIV2L Gene that Cause Trichohepatoenteric Syndrome 2

Frontiers in Genetics ◽

10.3389/fgene.2021.756451 ◽

2021 ◽

Vol 12 ◽

Author(s):

Qiao Zhang ◽

Xia Qian ◽

Jianli Zhou ◽

Lin Han ◽

Shaoming Zhou ◽

...

Keyword(s):

Failure To Thrive ◽

Tetratricopeptide Repeat ◽

Compound Heterozygous ◽

Whole Exome ◽

Causative Factors ◽

Novel Variants ◽

Repeat Domain ◽

Continuous Feeding ◽

Tetratricopeptide Repeat Domain ◽

Compound Heterozygous Variants

Background: Trichohepatoenteric syndrome (THES) is a rare disease that mainly causes intractable diarrhea. It is classified into THES1 and THES2, which are associated with the tetratricopeptide repeat domain 37 (TTC37) gene and Ski2-like RNA helicase (SKIV2L) gene, respectively. THES is not very prevalent in China or worldwide, but new cases have increasingly been reported.Methods and Results: Here, we report the clinical and genetic information of a 1.5-month-old girl who was admitted to our hospital due to diarrhea and failure to thrive. Whole-exome sequencing (WES) revealed novel compound-heterozygous variants of the SKIV2L gene, c.3602_3609delAGCGCCTG (p.Q1201Rfs*2), and c.1990A > G (p.T664A) as the causative factors, which were confirmed via Sanger sequencing. Upon continuous feeding with an amino-acid formula through a gastric tube and parenteral nutrition, the patient resumed thriving and her stool frequency decreased.Conclusion: We report a girl carrying novel variants of the SKIV2L gene that cause THES2, thereby providing valuable information on the diagnosis of THES2 and expanding the spectrum of disease-causing SKIV2L mutations.

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Identification and targeted management of a neurodegenerative disorder caused by biallelic mutations in SLC5A6

npj Genomic Medicine ◽

10.1038/s41525-019-0103-x ◽

2019 ◽

Vol 4 (1) ◽

Cited By ~ 1

Author(s):

Alicia B. Byrne ◽

Peer Arts ◽

Steven W. Polyak ◽

Jinghua Feng ◽

Andreas W. Schreiber ◽

...

Keyword(s):

Neurodegenerative Disorder ◽

Genetic Disorder ◽

Epileptic Encephalopathy ◽

Compound Heterozygous ◽

Whole Exome ◽

Sodium Dependent ◽

Neuromotor Function ◽

Vitamin Uptake ◽

Compound Heterozygous Variants ◽

Biallelic Mutations

AbstractWe describe a sibling pair displaying an early infantile-onset, progressive neurodegenerative phenotype, with symptoms of developmental delay and epileptic encephalopathy developing from 12 to 14 months of age. Using whole exome sequencing, compound heterozygous variants were identified in SLC5A6, which encodes the sodium-dependent multivitamin transporter (SMVT) protein. SMVT is an important transporter of the B-group vitamins biotin, pantothenate, and lipoate. The protein is ubiquitously expressed and has major roles in vitamin uptake in the digestive system, as well as transport of these vitamins across the blood–brain barrier. Pathogenicity of the identified variants was demonstrated by impaired biotin uptake of mutant SMVT. Identification of this vitamin transporter as the genetic basis of this disorder guided targeted therapeutic intervention, resulting clinically in improvement of the patient’s neurocognitive and neuromotor function. This is the second report of biallelic mutations in SLC5A6 leading to a neurodegenerative disorder due to impaired biotin, pantothenate and lipoate uptake. The genetic and phenotypic overlap of these cases confirms mutations in SLC5A6 as the genetic cause of this disease phenotype. Recognition of the genetic disorder caused by SLC5A6 mutations is essential for early diagnosis and to facilitate timely intervention by triple vitamin (biotin, pantothenate, and lipoate) replacement therapy.

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Novel variants in DNAH9 lead to nonsyndromic severe asthenozoospermia

Reproductive Biology and Endocrinology ◽

10.1186/s12958-021-00709-0 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Dongdong Tang ◽

Yanwei Sha ◽

Yang Gao ◽

Jingjing Zhang ◽

Huiru Cheng ◽

...

Keyword(s):

Sanger Sequencing ◽

Sperm Morphology ◽

Immunofluorescence Staining ◽

Compound Heterozygous ◽

Sperm Tail ◽

Transmission Electron ◽

Whole Exome ◽

Detailed Medical History ◽

Novel Variants ◽

Common Causes

Abstract Background Asthenozoospermia is one of the most common causes of male infertility, and its genetic etiology is poorly understood. DNAH9 is a core component of outer dynein arms in cilia and flagellum. It was reported that variants of DNAH9 (OMIM: 603330) might cause primary ciliary dyskinesia (PCD). However, variants in DNAH9 lead to nonsyndromic severe asthenozoospermia have yet to be reported. Methods Whole exome sequencing (WES) was performed for two individuals with nonsyndromic severe asthenozoospermia from two non-consanguineous families, and Sanger sequencing was performed to verify the identified variants and parental origins. Sperm routine analysis, sperm vitality rate and sperm morphology analysis were performed according the WHO guidelines 2010 (5th edition). Transmission electron microscopy (TEM, TECNAI-10, 80 kV, Philips, Holland) was used to observe ultrastructures of sperm tail. Quantitative realtime-PCR and immunofluorescence staining were performed to detect the expression of DNAH9-mRNA and location of DNAH9-protein. Furthermore, assisted reproductive procedures were applied. Results By WES and Sanger sequencing, compound heterozygous DNAH9 (NM_001372.4) variants were identified in the two individuals with nonsyndromic severe asthenozoospermia (F1 II-1: c.302dupT, p.Leu101fs*47 / c.6956A > G, p.Asp2319Gly; F2 II-1: c.6294 T > A, p.Phe2098Leu / c.10571 T > A, p.Leu3524Gln). Progressive rates less than 1% with normal sperm morphology rates and normal vitality rates were found in both of the two subjects. No respiratory phenotypes, situs inversus or other malformations were found by detailed medical history, physical examination and lung CT scans etc. Moreover, the expression of DNAH9-mRNA was significantly decreased in sperm from F1 II-1. And expression of DNAH9 is lower in sperm tail by immunofluorescence staining in F1 II-1 compared with normal control. Notably, by intracytoplasmic sperm injection (ICSI), F1 II-1 and his partner successfully achieved clinical pregnancy. Conclusions We identified DNAH9 as a novel pathogenic gene for nonsyndromic severe asthenospermia, and ICSI can contribute to favorable pregnancy outcomes for these patients.

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Dravet syndrome associated mutations in GABRA1, GABRB2 and GABRG2 define the genetic landscape of defects of GABAA receptors

Brain Communications ◽

10.1093/braincomms/fcab033 ◽

2021 ◽

Author(s):

Ciria C Hernandez ◽

XiaoJuan Tian ◽

Ningning Hu ◽

Wangzhen Shen ◽

Mackenzie A Catron ◽

...

Keyword(s):

Gabaa Receptor ◽

De Novo ◽

Epileptic Encephalopathy ◽

Dravet Syndrome ◽

First Year ◽

Genes Encoding ◽

Genetic Landscape ◽

Clonic Seizures ◽

Trafficking Defects ◽

First Year Of Life

Abstract Dravet syndrome is a rare, catastrophic epileptic encephalopathy that begins in the first year of life, usually with febrile or afebrile hemiclonic or generalized tonic-clonic seizures followed by status epilepticus. De novo variants in genes that mediate synaptic transmission such as SCN1A and PCDH19 are often associated with Dravet syndrome. Recently, GABAA receptor subunit genes (GABRs) encoding α1 (GABRA1), β3 (GABRB3) and γ2 (GABRG2), but not β2 (GABRB2) or β1 (GABRB1), subunits are frequently associated with Dravet syndrome or Dravet syndrome-like phenotype. We performed next generation sequencing on 870 patients with Dravet syndrome and identified nine variants in three different GABRs. Interestingly, the variants were all in genes encoding the most common GABAA receptor, the α1β2γ2 receptor. Mutations in GABRA1 (c.644T>C, p.L215P; c.640C>T, p.R214C; c.859G>A; V287I; c.641G>A, p.R214H) and GABRG2 (c.269C>G, p.T90R; c.1025C>T, p.P342L) presented as de novo cases, while in GABRB2 two variants were de novo (c.992T>C, p.F331S; c.542A>T, p.Y181F) and one was autosomal dominant and inherited from the maternal side (c.990_992del, p.330_331del). We characterized the effects of these GABR variants on GABAA receptor biogenesis and channel function. We found that defects in receptor gating were the common deficiency of GABRA1 and GABRB2 Dravet syndrome variants, while mainly trafficking defects were found with the GABRG2 (c.269C>G, p.T90R) variant. It seems that variants in α1 and β2 subunits are less tolerated than in γ2 subunits, since variant α1 and β2 subunits express well but were functionally deficient. This suggests that all of these GABR variants are all targeting GABR genes that encode the assembled α1β2γ2 receptor, and regardless of which of the three subunits are mutated, variants in genes coding for α1, β2 and γ2 receptor subunits make them candidate causative genes in the pathogenesis of Dravet syndrome.

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A novel LOXHD1 variant in a Chinese couple with hearing loss

Journal of International Medical Research ◽

10.1177/0300060519884197 ◽

2019 ◽

Vol 47 (12) ◽

pp. 6082-6090 ◽

Cited By ~ 1

Author(s):

Chuan Zhang ◽

Shengju Hao ◽

Yali Liu ◽

Bingbo Zhou ◽

Furong Liu ◽

...

Keyword(s):

Hearing Loss ◽

Molecular Diagnosis ◽

Protein Function ◽

Mexican American ◽

Compound Heterozygous ◽

Congenital Hearing Loss ◽

Targeted Next Generation Sequencing ◽

Novel Variants ◽

Novel Variant ◽

Compound Heterozygous Variants

Objective To perform molecular diagnosis and genetic counseling in a young Chinese couple with congenital hearing loss. Methods Variant screening analysis was performed by PCR and direct Sanger sequencing or targeted next-generation sequencing of all known hearing loss genes. Novel variants were evaluated by PolyPhen2 and PROVEAN software tools to evaluate possible effects on protein function. Results We identified causative variants in the young couple: c.235delC (rs80338943)/c.299-300delAT (rs111033204) compound heterozygous variants of GJB2 in the husband and c.1828G>A (p.Glu610Lys, rs535637788)/c.2825-2827delAGA compound heterozygous variants of LOXHD1 in the wife. The LOXHD1 c.1828G>A variant has only previously been reported in a Mexican-American individual in the 1000 Genomes Project database. Using PolyPhen2 and PROVEAN, we speculated that the LOXHD1 variant c.1828G>A is potentially pathogenic. Conclusion We carried out molecular diagnosis in a young couple with congenital hearing loss, and identified different disease-causing genes in the two individuals. The LOXHD1 variant c.1828G>A present in the wife had not previously been reported in individuals with congenital hearing loss. We determined this to be a potential pathogenic variant, and a novel variant associated with hearing loss in a Chinese individual.

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Clinical and Pathological Features of a Newborn With Compound Heterozygous ANKS6 Variants

Pediatric and Developmental Pathology ◽

10.1177/1093526619881541 ◽

2019 ◽

Vol 23 (3) ◽

pp. 235-239

Author(s):

Sakil Kulkarni ◽

Brooj Abro ◽

Maria Laura Duque Lasio ◽

Janis Stoll ◽

Dorothy K Grange ◽

...

Keyword(s):

Cardiac Failure ◽

Renal Dysplasia ◽

Cardiomyocyte Hypertrophy ◽

Compound Heterozygous ◽

Pathogenic Variants ◽

Whole Exome ◽

Genes Encoding ◽

Cystic Renal Dysplasia ◽

Cystic Renal Disease ◽

Compound Heterozygous Variants

We report a term female infant born to nonconsanguineous parents who presented with renal failure at birth, hypothyroidism, cholestasis, and progressive cardiac dysfunction. Multigene next-generation sequencing panels for cholestasis, cardiomyopathy, and cystic renal disease did not reveal a unifying diagnosis. Whole exome sequencing revealed compound heterozygous pathogenic variants in ANKS6 (Ankyrin Repeat and Sterile Alpha Motif Domain Containing 6), which encodes a protein that interacts with other proteins of the Inv compartment of cilium ( NEK8, NPHP2/INVS, and NPHP3). ANKS6 has been shown to be important for early renal development and cardiac looping in animal models. Autopsy revealed cystic renal dysplasia and cardiomyocyte hypertrophy, disarray, and focal necrosis. Liver histology revealed cholestasis and centrilobular necrosis, which was likely a result of progressive cardiac failure. This is the first report of compound heterozygous variants in ANKS6 leading to a nephronopthisis-related ciliopathy-like phenotype. We conclude that pathogenic variants in ANKS6 may present early in life with severe renal and cardiac failure, similar to subjects with variants in genes encoding other proteins in the Inv compartment of the cilium.

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