Mutational Analysis of Compound Heterozygous Mutation P.q6x/p.h232r in Srd5a2 Causing 46,xy Disorder of Sex Development

Background: Over 100 mutations in the SRD5A2 gene have been identified in subjects with 46,XY disorder of sex development (DSD). Exploration of SRD5A2 mutations and elucidation of the molecular mechanisms behind their effects should reveal the functions of the domains of the 5α-reductase 2 enzyme and identify the cause of 46,XY DSD. Previously, we reported a novel compound heterozygous p.Q6X/p.H232R mutation of the SRD5A2 gene in a case with 46,XY DSD. Whether the compound heterozygous p.Q6X/p.H232R mutation in this gene causes 46,XY DSD requires further exploration. Results: To clarify the cause of 46,XY DSD in the affected family focused on here, SRD5A2 sequencing was performed. Heterozygous p.H232R mutation was identified in the proband’s father, so we concluded that this mutation originated from the paternal side of the family and did not cause 46,XY DSD. Meanwhile, heterozygous p.Q6X mutation was identified in the proband’s mother, maternal uncle, and maternal grandfather, indicating that this mutation originated from maternal side of the family and did not cause 46,XY DSD. To clarify the effect of the p.H232R mutation in SRD5A2 on dihydrotestosterone (DHT) production, p.H232R mutant SRD5A2 plasmids were transfected into HEK293 cells. LC-MS indicated that DHT production decreased compared with that in cells transfected with wild-type SRD5A2.Conclusions: Our findings confirmed that the compound heterozygous p.Q6X/p.H232R mutation in the SRD5A2 gene is the cause of 46,XY DSD. p.H232R mutation reduced DHT production while attenuating the catalytic efficiency of the 5α-reductase 2 enzyme.

Vasculitis in a patient with mevalonate kinase deficiency (MKD): a case report

Background Mevalonate kinase deficiency (MKD) is a rare autoinflammatory condition caused by biallelic loss-of-function (LOF) mutations in mevalonate kinase (MVK) gene encoding the enzyme mevalonate kinase. Patients with MKD display a variety of non-specific clinical manifestations, which can lead to diagnostic delay. We report the case of a child presenting with vasculitis that was found by genetic testing to be caused by MKD, and now add this autoinflammatory disease to the ever-expanding list of causes of monogenic vasculitides. Case presentation A 2-year-old male presented with an acute 7-day history of high-grade fever, abdominal pain, diarrhoea, rectal bleeding and extensive purpuric and necrotic lesions, predominantly affecting the lower limbs. He had been suffering from recurrent episodes of fever from early in infancy, associated with maculopapular/petechial rashes triggered by intercurrent infection, and after vaccines. Extensive infection screen was negative. Skin biopsy revealed small vessel vasculitis. Visceral digital subtraction arteriography was normal. With a diagnosis of severe idiopathic cutaneous vasculitis, he was treated with corticosteroids and mycophenolate mofetil. Despite that his acute phase reactants remained elevated, fever persisted and the vasculitic lesions progressed. Next-generation sequencing revealed compound heterozygous mutation in MVK c.928G > A (p.V310M) and c.1129G > A (p.V377I) while reduced mevalonate enzyme activity was confirmed suggesting a diagnosis of MKD as a cause of the severe vasculitis. Prompt targeted treatment with IL-1 blockade was initiated preventing escalation to more toxic vasculitis therapies and reducing unnecessary exposure to cytotoxic treatment. Conclusions Our report highlights the broad clinical phenotype of MKD that includes severe cutaneous vasculitis and emphasizes the need to consider early genetic screening for young children presenting with vasculitis to exclude a monogenic vasculitis which may be amenable to targeted treatment.

Aicardi-Goutières Syndrome due to a SAMHD1 Mutation Presenting with Deep White Matter Cysts

We report on the first Polish patient diagnosed with the Aicardi-Goutières syndrome 5 (AGS5). AGS is caused by mutations in one of 9 genes (<i>TREX1</i>, <i>RNASEH2A</i>, <i>RNASEH2B</i>, <i>RNASEH2C</i>, <i>SAMHD1</i>, <i>ADAR</i>, <i>IFIH</i>, <i>LSM11</i>, <i>RNU7-1</i>) which stimulate the type I interferon response. The diagnosis was confirmed by identifying a compound heterozygous mutation p.(Phe165Ser)/p.(Gln235*) in the <i>SAMHD1</i> gene using whole-exome sequencing. The cystic lesions in the temporal lobes are an uncommon finding in the presented patient carrying a <i>SAMHD1</i> mutation. Reporting new cases expands the range of phenotypes and plays the crucial role in understanding the AGS pathogenesis and creates new therapy approaches.

Case Report: A Novel Compound Heterozygous Mutation of the FRMD4A Gene Identified in a Chinese Family With Global Developmental Delay, Intellectual Disability, and Ataxia

Background: FERM domain-containing protein 4A (FRMD4A) is a scaffolding protein previously proposed to be critical in the regulation of cell polarity in neurons and implicated in human intellectual development.Case Presentation: We report a case of a 3-year-old boy with corpus callosum anomaly, relative macrocephaly, ataxia, and unexplained global developmental delay. Here, compound heterozygous missense mutations in the FRMD4A gene [c.1830G&gt;A, p.(Met610Ile) and c.2973G&gt;C, p.(Gln991His)] were identified in the proband, and subsequent familial segregation showed that each parent had transmitted a mutation.Conclusions: Our results have confirmed the associations of mutations in the FRMD4A gene with intellectual development and indicated that for patients with unexplained global developmental delay, the FRMD4A gene should be included in the analysis of whole exome sequencing data, which can contribute to the identification of more patients affected by this severe phenotypic spectrum.

Patient-Specific iPSC-Derived Neural Differentiated and Hepatocyte-like Cells, Carrying the Compound Heterozygous Mutation p.V1023Sfs*15/p.G992R, Present the “Variant” Biochemical Phenotype of Niemann-Pick Type C1 Disease

Niemann–Pick disease type C1 (NP-C1) is a rare lysosomal storage disorder caused by autosomal recessive mutations in the NPC1 gene. Patients display a wide spectrum on the clinical as well as on the molecular level, wherein a so-called “variant” biochemical phenotype can be observed. Here, we report an in vitro analysis of fibroblasts obtained from an NP-C1 patient carrying the undescribed compound heterozygous mutation p.V1023Sfs*15/p.G992R. Since NP-C1 is a neurovisceral disease and the patient suffers from severe neurological as well as hepatic symptoms, we extended our study to neural differentiated and hepatocyte-like cells derived from patient-specific induced pluripotent stem cells. We detected slightly increased intracellular cholesterol levels compared to the control cell line in fibroblasts, neural differentiated and hepatocyte-like cells, suggesting a “variant” biochemical phenotype. Furthermore, the total NPC1 protein, as well as post-ER glycoforms of the NPC1 protein, tended to be reduced. In addition, colocalization analysis revealed a mild reduction of the NPC1 protein in the lysosomes. The patient was diagnosed with NP-C1 at the age of 34 years, after an initial misdiagnosis of schizophrenia. After years of mild and unspecific symptoms, such as difficulties in coordination and concentration, symptoms progressed and the patient finally presented with ataxia, dysarthria, dysphagia, vertical supranuclear gaze palsy, and hepatosplenomegaly. Genetic testing finally pointed towards an NP-C1 diagnosis, revealing the so-far undescribed compound heterozygous mutation p.V1023Sfs*15/p.G992R in the NPC1 gene. In light of these findings, this case provides support for the p.G992R mutation being causative for a “variant” biochemical phenotype leading to an adult-onset type of NP-C1 disease.

Hereditary Spherocytosis Caused by a Novel Compound Heterozygous Mutation of the SPTA1 Gene and Autoimmune Hepatitis in a Pediatric Patient

Objective: Patients suffering from both hereditary spherocytosis (HS) and autoimmune hepatitis (AIH) are very rare. We analyzed the clinical and genetic characteristics of a seven-year-old girl with yellow sclerae and abnormal liver function tests, but no further symptoms. Methods: Blood samples were collected from the proband, her parents, and her paternal grandmother, and analyzed using routine laboratory tests, as well as subjected to next-generation and Sanger sequencing.Results: Compound heterozygous mutations of the spectrin alpha, erythrocytic 1 (SPTA1) gene were identified in the proband. Thec.134G>A (p.R45K) and c.6544G>C (p.D2182H) mutations were inherited from her mother and father, respectively. The proband’s father and paternal grandmother had the same mutation. Neither mutation is described in the Human Gene Mutation Database. Conclusions: HS has clinical manifestations similar to AIH, it may be difficult to diagnose when it coexists with AIH. When laboratory results cannot be explained by autoimmune liver disease alone, the possibility of a concomitant disease should be considered. Pedigree investigation and genetic analyses might be required to arrive at the final diagnosis.