scholarly journals A frameshift insertion in FA2H causes a recessively inherited form of ichthyosis congenita in Chianina cattle

2021 ◽  
Author(s):  
Joana G. P. Jacinto ◽  
Irene M. Häfliger ◽  
Inês M. B. Veiga ◽  
Anna Letko ◽  
Arcangelo Gentile ◽  
...  
Keyword(s):  
Mammalian Species ◽  
Clinical Signs ◽  
Homozygosity Mapping ◽  
Recessive Trait ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Identical By Descent ◽  
Lethal Allele ◽  
Heterozygous Carriers ◽  
Myelin Disorders

AbstractThe aim of this study was to characterize the phenotype and to identify the genetic etiology of a syndromic form of ichthyosis congenita (IC) observed in Italian Chianina cattle and to estimate the prevalence of the deleterious allele in the population. Sporadic occurrence of different forms of ichthyosis including IC have been previously reported in cattle. However, so far, no causative genetic variant has been found for bovine IC. Nine affected cattle presenting congenital xerosis, hyperkeratosis and scaling of the skin as well as urolithiasis and cystitis associated with retarded growth were examined. Skin histopathology revealed a severe, diffuse orthokeratotic hyperkeratosis with mild to moderate epidermal hyperplasia. The pedigree records indicated a monogenic recessive trait. Homozygosity mapping and whole-genome sequencing allowed the identification of a homozygous frameshift 1 bp insertion in the FA2H gene (c.9dupC; p.Ala4ArgfsTer142) located in a 1.92 Mb shared identical-by-descent region on chromosome 18 present in all cases, while the parents were heterozygous as expected for obligate carriers. These findings enable the selection against this sub-lethal allele showing an estimated frequency of ~ 7.5% in Chianina top sires. A sporadic incidence of mild clinical signs in the skin of heterozygous carriers was observed. So far, pathogenic variants affecting the encoded fatty acid 2-hydroxylase catalyzing the synthesis of 2-hydroxysphingolipids have been associated with myelin disorders. In conclusion, this study represents the first report of an FA2H-related autosomal recessive inherited skin disorder in a mammalian species and adds FA2H to the list of candidate genes for ichthyosis in humans and animals. Furthermore, this study provides a DNA-based diagnostic test that enables selection against the identified pathogenic variant in the Chianina cattle population. However, functional studies are needed to better understand the expression of FA2H in IC-affected Chianina cattle.

scholarly journals Reassessment of Gene-Elusive Familial Dilated Cardiomyopathy Leading to the Discovery of a Homozygous AARS2 Variant—The Importance of Regular Reassessment of Genetic Findings

2021 ◽  
Vol 11 (3) ◽  
pp. 122-128
Author(s):  
Priya Bhardwaj ◽  
Christoffer Rasmus Vissing ◽  
Niels Kjær Stampe ◽  
Kasper Rossing ◽  
Alex Hørby Christensen ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Genetic Screening ◽  
Sanger Sequencing ◽  
Mitochondrial Protein ◽  
Trna Synthetase ◽  
Familial Dilated Cardiomyopathy ◽  
Pathogenic Variants ◽  
Case Summary ◽  
Heterozygous Carriers ◽  
Important Enzyme

Background: AARS2 encodes the mitochondrial protein alanyl-tRNA synthetase 2 (MT-AlaRS), an important enzyme in oxidative phosphorylation. Variants in AARS2 have previously been associated with infantile cardiomyopathy. Case summary: A 4-year-old girl died of infantile-onset dilated cardiomyopathy (DCM) in 1996. Fifteen years later, her 21-year-old brother was diagnosed with DCM and ultimately underwent heart transplantation. Initial sequencing of 15 genes discovered no pathogenic variants in the brother at the time of his diagnosis. However, 9 years later re-screening in an updated screening panel of 129 genes identified a homozygous AARS2 (c.1774C > T) variant. Sanger sequencing of the deceased girl confirmed her to be homozygous for the AARS2 variant, while both parents and a third sibling were all found to be unaffected heterozygous carriers of the AARS2 variant. Discussion: This report underlines the importance of repeated and extended genetic screening of elusive families with suspected hereditary cardiomyopathies, as our knowledge of disease-causing mutations continuously grows. Although identification of the genetic etiology in the reported family would not have changed the clinical management, the genetic finding allows genetic counselling and holds substantial value in identifying at-risk relatives.

scholarly journals A novel de novo DDX3X missense variant in a female with brachycephaly and intellectual disability: a case report

2021 ◽  
Vol 47 (1) ◽  
Author(s):  
Giada Moresco ◽  
Jole Costanza ◽  
Carlo Santaniello ◽  
Ornella Rondinone ◽  
Federico Grilli ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Clinical Presentation ◽  
De Novo ◽  
Clinical Signs ◽  
Missense Variant ◽  
Psychomotor Development ◽  
Helicase Domain ◽  
Protein Activity ◽  
Mrna Metabolism ◽  
Pathogenic Variants

Abstract Background De novo pathogenic variants in the DDX3X gene are reported to account for 1–3% of unexplained intellectual disability (ID) in females, leading to the rare disease known as DDX3X syndrome (MRXSSB, OMIM #300958). Besides ID, these patients manifest a variable clinical presentation, which includes neurological and behavioral defects, and abnormal brain MRIs. Case presentation We report a 10-year-old girl affected by delayed psychomotor development, delayed myelination, and polymicrogyria (PMG). We identified a novel de novo missense mutation in the DDX3X gene (c.625C > G) by whole exome sequencing (WES). The DDX3X gene encodes a DEAD-box ATP-dependent RNA-helicase broadly implicated in gene expression through regulation of mRNA metabolism. The identified mutation is located just upstream the helicase domain and is suggested to impair the protein activity, thus resulting in the altered translation of DDX3X-dependent mRNAs. The proband, presenting with the typical PMG phenotype related to the syndrome, does not show other clinical signs frequently reported in presence of missense DDX3X mutations that are associated with a most severe clinical presentation. In addition, she has brachycephaly, never described in female DDX3X patients, and macroglossia, that has never been associated with the syndrome. Conclusions This case expands the knowledge of DDX3X pathogenic variants and the associated DDX3X syndrome phenotypic spectrum.

scholarly journals Janus-faced EPHB4-associated disorders: novel pathogenic variants and unreported intrafamilial overlapping phenotypes

2021 ◽  
Author(s):  
Silvia Martin-Almedina ◽  
Kazim Ogmen ◽  
Ege Sackey ◽  
Dionysios Grigoriadis ◽  
Christina Karapouliou ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Fetal Hydrops ◽  
Clinical Phenotypes ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Disease Mechanisms ◽  
Novel Variants ◽  
Uncertain Significance ◽  
Clinical Phenotyping

Abstract Purpose Several clinical phenotypes including fetal hydrops, central conducting lymphatic anomaly or capillary malformations with arteriovenous malformations 2 (CM-AVM2) have been associated with EPHB4 (Ephrin type B receptor 4) variants, demanding new approaches for deciphering pathogenesis of novel variants of uncertain significance (VUS) identified in EPHB4, and for the identification of differentiated disease mechanisms at the molecular level. Methods Ten index cases with various phenotypes, either fetal hydrops, CM-AVM2, or peripheral lower limb lymphedema, whose distinct clinical phenotypes are described in detail in this study, presented with a variant in EPHB4. In vitro functional studies were performed to confirm pathogenicity. Results Pathogenicity was demonstrated for six of the seven novel EPHB4 VUS investigated. A heterogeneity of molecular disease mechanisms was identified, from loss of protein production or aberrant subcellular localization to total reduction of the phosphorylation capability of the receptor. There was some phenotype–genotype correlation; however, previously unreported intrafamilial overlapping phenotypes such as lymphatic-related fetal hydrops (LRFH) and CM-AVM2 in the same family were observed. Conclusion This study highlights the usefulness of protein expression and subcellular localization studies to predict EPHB4 variant pathogenesis. Our accurate clinical phenotyping expands our interpretation of the Janus-faced spectrum of EPHB4-related disorders, introducing the discovery of cases with overlapping phenotypes.

scholarly journals Spondylocarpotarsal synostosis syndrome due to a novel loss of function FLNB variant: a case report

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Samina Yasin ◽  
Outi Makitie ◽  
Sadaf Naz
Keyword(s):  
Short Stature ◽  
Autosomal Recessive ◽  
Autosomal Recessive Disorder ◽  
Loss Of Function ◽  
Case Presentation ◽  
Pathogenic Variants ◽  
Skeletal Malformations ◽  
Tarsal Bones ◽  
The Family ◽  
Heterozygous Carriers

Abstract Background Loss of function or gain of function variants of Filamin B (FLNB) cause recessive or dominant skeletal disorders respectively. Spondylocarpotarsal synostosis syndrome (SCT) is a rare autosomal recessive disorder characterized by short stature, fused vertebrae and fusion of carpal and tarsal bones. We present a novel FLNB homozygous pathogenic variant and present a carrier of the variant with short height. Case presentation We describe a family with five patients affected with skeletal malformations, short stature and vertebral deformities. Exome sequencing revealed a novel homozygous frameshift variant c.2911dupG p.(Ala971GlyfsTer122) in FLNB, segregating with the phenotype in the family. The variant was absent in public databases and 100 ethnically matched control chromosomes. One of the heterozygous carriers of the variant had short stature. Conclusion Our report expands the genetic spectrum of FLNB pathogenic variants. It also indicates a need to assess the heights of other carriers of FLNB recessive variants to explore a possible role in idiopathic short stature.

scholarly journals CNNM2-Related Disorders: Phenotype and Its Severity Were Associated With the Mode of Inheritance

2021 ◽  
Vol 9 ◽  
Author(s):  
Han Zhang ◽  
Ye Wu ◽  
Yuwu Jiang
Keyword(s):  
De Novo ◽  
Serum Magnesium ◽  
Brain Magnetic Resonance Imaging ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Significant Difference ◽  
Domain Variations ◽  
Type 3

CNNM2 (Cystathionine-β-synthase-pair Domain Divalent Metal Cation Transport Mediator 2) pathogenic variants have been reported to cause hypomagnesemia, epilepsy, and intellectual disability/developmental delay (ID/DD). We identified two new cases with CNNM2 novel de novo pathogenic variants, c.814T>C and c.976G>C. They both presented with infantile-onset epilepsy with DD and hypomagnesemia refractory to magnesium supplementation. To date, 21 cases with CNNM2-related disorders have been reported. We combined all 23 cases to analyze the features of CNNM2-related disorders. The phenotypes can be classified into three types: type 1, autosomal dominant (AD) inherited simple hypomagnesemia; type 2, AD inherited hypomagnesemia with epilepsy and ID/DD; and type 3, autosomal recessive (AR) inherited hypomagnesemia with epilepsy and ID/DD. All five type 1 cases had no epilepsy or ID/DD; they all had hypomagnesemia, and three of them presented with symptoms secondary to hypomagnesemia. Fifteen type 2 patients could have ID/DD and seizures, which can be controlled with antiseizure medications (ASMs); their variations clustered in the DUF21 domain of CNNM2. All three type 3 patients had seizures from 1 to 6 days after birth; the seizures were refractory, and 1/3 had status epilepticus; ID/DD in these AR-inherited cases was more severe than that of AD-inherited cases; they all had abnormalities of brain magnetic resonance imaging (MRI). Except for one patient whose serum magnesium was the lower limit of normal, others had definite hypomagnesemia. Hypomagnesemia could be improved after magnesium supplement but could not return to the normal level. Variations in the CBS2 domain may be related to lower serum magnesium. However, there was no significant difference in the level of serum magnesium among the patients with three different types of CNNM2-related disorders. The severity of different phenotypes was therefore not explained by decreased serum magnesium. We expanded the spectrum of CNNM2 variants and classified the phenotypes of CNNM2-related disorders into three types. We found that DUF21 domain variations were most associated with CNNM2-related central nervous system phenotypes, whereas hypomagnesemia was more pronounced in patients with CBS2 domain variations, and AR-inherited CNNM2-related disorders had the most severe phenotype. These results provide important clues for further functional studies of CNNM2 and provide basic foundations for more accurate genetic counseling.

scholarly journals Exploring the Genotype–Phenotype Correlation in GBA-Parkinson Disease: Clinical Aspects, Biomarkers, and Potential Modifiers

2021 ◽  
Vol 12 ◽  
Author(s):  
Elisa Menozzi ◽  
Anthony H. V. Schapira
Keyword(s):  
Parkinson Disease ◽  
Progressive Disease ◽  
Clinical Aspects ◽  
Compound Heterozygous ◽  
Pathogenic Variants ◽  
Risk Variants ◽  
Increased Risk ◽  
Severe Motor ◽  
Heterozygous Carriers

Variants in the glucocerebrosidase (GBA) gene are the most common genetic risk factor for Parkinson disease (PD). These include pathogenic variants causing Gaucher disease (GD) (divided into “severe,” “mild,” or “complex”—resulting from recombinant alleles—based on the phenotypic effects in GD) and “risk” variants, which are not associated with GD but nevertheless confer increased risk of PD. As a group, GBA-PD patients have more severe motor and nonmotor symptoms, faster disease progression, and reduced survival compared with noncarriers. However, different GBA variants impact variably on clinical phenotype. In the heterozygous state, “complex” and “severe” variants are associated with a more aggressive and rapidly progressive disease. Conversely, “mild” and “risk” variants portend a more benign course. Homozygous or compound heterozygous carriers usually display severe phenotypes, akin to heterozygous “complex” or “severe” variants carriers. This article reviews genotype–phenotype correlations in GBA-PD, focusing on clinical and nonclinical aspects (neuroimaging and biochemical markers), and explores other disease modifiers that deserve consideration in the characterization of these patients.

scholarly journals Reverse Phenotyping after Whole-Exome Sequencing in Steroid-Resistant Nephrotic Syndrome

2019 ◽  
Vol 15 (1) ◽  
pp. 89-100 ◽  
Author(s):  
Samuela Landini ◽  
Benedetta Mazzinghi ◽  
Francesca Becherucci ◽  
Marco Allinovi ◽  
Aldesia Provenzano ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Clinical Signs ◽  
Long Term Outcome ◽  
Steroid Resistant ◽  
Steroid Resistant Nephrotic Syndrome ◽  
Pathogenic Variants ◽  
Whole Exome ◽  
Steroid Sensitive

Background and objectivesNephrotic syndrome is a typical presentation of genetic podocytopathies but occasionally other genetic nephropathies can present as clinically indistinguishable phenocopies. We hypothesized that extended genetic testing followed by reverse phenotyping would increase the diagnostic rate for these patients.Design, setting, participants, & measurementsAll patients diagnosed with nephrotic syndrome and referred to our center between 2000 and 2018 were assessed in this retrospective study. When indicated, whole-exome sequencing and in silico filtering of 298 genes related to CKD were combined with subsequent reverse phenotyping in patients and families. Pathogenic variants were defined according to current guidelines of the American College of Medical Genetics.ResultsA total of 111 patients (64 steroid-resistant and 47 steroid-sensitive) were included in the study. Not a single pathogenic variant was detected in the steroid-sensitive group. Overall, 30% (19 out of 64) of steroid-resistant patients had pathogenic variants in podocytopathy genes, whereas a substantial number of variants were identified in other genes, not commonly associated with isolated nephrotic syndrome. Reverse phenotyping, on the basis of a personalized diagnostic workflow, permitted to identify previously unrecognized clinical signs of an unexpected underlying genetic nephropathy in a further 28% (18 out of 64) of patients. These patients showed similar multidrug resistance, but different long-term outcome, when compared with genetic podocytopathies.ConclusionsReverse phenotyping increased the diagnostic accuracy in patients referred with the diagnosis of steroid-resistant nephrotic syndrome.

scholarly journals Hereditary C2 deficiency: Genetic studies and association with the HL-A system.

1975 ◽  
Vol 141 (6) ◽  
pp. 1464-1469 ◽  
Author(s):  
N K Day ◽  
R L'Esperance ◽  
R A Good ◽  
A F Michael ◽  
J A Hansen ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Genetic Factors ◽  
Recessive Trait ◽  
Autosomal Recessive Trait ◽  
Systemic Lupus ◽  
Genetic Studies ◽  
Large Pedigree ◽  
Deficient Patient ◽  
Heterozygous Carriers ◽  
C2 Deficiency

Herediatary C2-deficiency has been shown to be transmitted asn an autosomal recessive characteristic. Recent evidence indicates that some genetic factors involved in the control of the complement (C) system in both man and mice are governed by genes localized within the major histocompatibility regionmthis study describes a large pedigree of the paternal family of a C2-deficient patient with systemic lupus erythematosusl It is shown that this condition is transmitted as an autosomal recessive trait, the heterozygous carriers having approximately half normal levels of C2. Furthermore, this trait was shown to be inherited in close linkage with an infrequent HL-A typw, 2,4A2. The maternal, C2-defective chromosome was shown to be transmitted by HL-AW10, W18 haplotypemthis same haplotype was described in a similar study by Fu et al. (6) to be associated with C2 deficiencymfinally, a third haplotype HL-A2,W18 carrying a defective C2 gene was demonstrated in a part of this pedigree.

A novel homozygous frameshift variant in the cellular retinaldehyde-binding protein 1 (RLBP1) gene causes retinitis punctata albescens

2020 ◽  
pp. 112067212091906
Author(s):  
Sónia Torres-Costa ◽  
Carla Sofia Ferreira ◽  
Ana Grangeia ◽  
Renato Santos-Silva ◽  
Elisete Brandão ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Anterior Segment ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Ocular Symptoms ◽  
Retinitis Punctata Albescens ◽  
Rod System ◽  
Causal Variants ◽  
Recessive Transmission ◽  
Caucasian Female

Background Retinitis punctata albescens is a form of retinitis pigmentosa characterized by white fleck-like deposits in the fundus, in most cases caused by pathogenic variants in RLBP1 gene. The purpose of this work is to report the phenotypic and genotypic data of a patient with retinitis punctata albescens carrying a deletion in the RLBP1 gene. Results An 8-year-old Caucasian female has been complaining of nyctalopia for the last 2 years. No other ocular symptoms were present. No relevant past medical or familiar history was described. At clinical examination, the patient’s best-corrected visual acuity was 20/20 in both eyes. Anterior segment evaluation and intraocular pressure were normal in both eyes. At fundoscopy, multiple punctate whitish-yellow fleck-like lesions were observed in the proximity of temporal superior and inferior vascular arcades. Scotopic electroretinogram demonstrated severely reduced rod response, without improvement or recovery of rod system function after prolonged dark adaptation. Blood DNA samples of this patient and from her parents were screened for causal variants in RLBP1, RDH5, and PRPH2. Conclusion A probable pathogenic frameshift variant was identified in homozygosity in the RLBP1 gene with an autosomal recessive transmission as another cause of retinitis punctata albescens. This DNA variant will aid ongoing functional studies and add to our understanding of the molecular pathology about RLBP1-associated retinopathies.

scholarly journals Mutational Spectrum Analysis of Seven Genes Associated with Thyroid Dyshormonogenesis

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Xi Chen ◽  
Xiaohong Kong ◽  
Jie Zhu ◽  
Tingting Zhang ◽  
Yanwei Li ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Genetic Alterations ◽  
Chinese Patients ◽  
Study Cohort ◽  
Chinese Han ◽  
Hormone Synthesis ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Thyroid Dyshormonogenesis ◽  
Generation Sequencing

Objective. Thyroid dyshormonogenesis (DH) is a genetically heterogeneous inherited disorder caused by thyroid hormone synthesis abnormalities. This study aims at comprehensively characterizing the mutation spectrum in Chinese patients with DH. Subjects and Methods. We utilized next-generation sequencing to screen for mutations in seven DH-associated genes (TPO, DUOX2, TG, DUOXA2, SLC26A4, SLC5A5, and IYD) in 21 Chinese Han patients with DH from Xinjiang Province. Results. Twenty-eight rare nonpolymorphic variants were found in 19 patients (90.5%), including 19, 5, 3, and 1 variants in DUOX2, TG, DUOXA2, and SLC26A4, respectively. Thirteen (62%) patients carried monogenic mutations, and six (28.5%) carried oligogenic mutations. Fifteen (71%) patients carried 2 or more DUOX2 (14) or DUOXA2 (1) variants. The genetic basis of DH in nine (43%) patients harboring biallelic or triallelic pathogenic variants was resolved. Seventeen patients (81%) carried DUOX2 mutations, most commonly p.R1110Q or p.K530X. No correlations were found between DUOX2 mutation types or numbers and clinical phenotypes. Conclusions. DUOX2 mutations were the most predominant genetic alterations of DH in the study cohort. Oligogenicity may explain the genetic basis of disease in many DH patients. Functional studies and further clinical studies with larger DH patient cohorts are needed to validate the roles of the mutations identified in this study.

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