scholarly journals Allele-specific mitochondrial stress induced by Multiple Mitochondrial Dysfunctions Syndrome 1 pathogenic mutations modeled in Caenorhabditis elegans

PLoS Genetics ◽  
2021 ◽  
Vol 17 (8) ◽  
pp. e1009771
Author(s):  
Peter A. Kropp ◽  
Jing Wu ◽  
Michael Reidy ◽  
Sanjay Shrestha ◽  
Kyle Rhodehouse ◽  
...  
Keyword(s):  
Autosomal Recessive Disorder ◽  
Orthologous Gene ◽  
Compound Heterozygous ◽  
Allelic Series ◽  
Interaction Domain ◽  
Respiratory Dysfunction ◽  
Mitochondrial Dysfunctions ◽  
Reactive Iron ◽  
Pathogenic Variants ◽  
Iron Sulfur

Multiple Mitochondrial Dysfunctions Syndrome 1 (MMDS1) is a rare, autosomal recessive disorder caused by mutations in the NFU1 gene. NFU1 is responsible for delivery of iron-sulfur clusters (ISCs) to recipient proteins which require these metallic cofactors for their function. Pathogenic variants of NFU1 lead to dysfunction of its target proteins within mitochondria. To date, 20 NFU1 variants have been reported and the unique contributions of each variant to MMDS1 pathogenesis is unknown. Given that over half of MMDS1 individuals are compound heterozygous for different NFU1 variants, it is valuable to investigate individual variants in an isogenic background. In order to understand the shared and unique phenotypes of NFU1 variants, we used CRISPR/Cas9 gene editing to recreate exact patient variants of NFU1 in the orthologous gene, nfu-1 (formerly lpd-8), in C. elegans. Five mutant C. elegans alleles focused on the presumptive iron-sulfur cluster interaction domain were generated and analyzed for mitochondrial phenotypes including respiratory dysfunction and oxidative stress. Phenotypes were variable between the mutant nfu-1 alleles and generally presented as an allelic series indicating that not all variants have lost complete function. Furthermore, reactive iron within mitochondria was evident in some, but not all, nfu-1 mutants indicating that iron dyshomeostasis may contribute to disease pathogenesis in some MMDS1 individuals.

scholarly journals The genetic basis of classical galactosaemia in Polish patients

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Aleksandra Jezela-Stanek ◽  
Anna Bauer ◽  
Katarzyna Wertheim-Tysarowska ◽  
Jerzy Bal ◽  
Agnieszka Magdalena Rygiel ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Genetic Basis ◽  
Dna Analysis ◽  
Current Knowledge ◽  
Autosomal Recessive Disorder ◽  
Molecular Characteristics ◽  
Compound Heterozygous ◽  
Classic Galactosemia ◽  
Pathogenic Variants ◽  
Molecular Etiology

AbstractClassic galactosemia (OMIM #230400) is an autosomal recessive disorder caused by homozygous or compound heterozygous pathogenic variants in the galactose-1-phosphate uridylyltransferase gene (GALT; 606999) on chromosome 9p13. Its diagnosis is established by detecting elevated erythrocyte galactose-1-phosphate concentration, reduced erythrocyte galactose-1-phosphate uridylyltransferase (GALT) enzyme activity. Biallelic pathogenic variants in the GALT gene is confirmed by DNA analysis. Our paper presents molecular characteristics of 195 Polish patients diagnosed with galactosemia I, intending to expand the current knowledge of this rare disease's molecular etiology. To the best of our knowledge, the described cohort of galactosemia patients is the largest single-center cohort presented so far.

scholarly journals Two Decades after Mandibuloacral Dysplasia Discovery: Additional Cases and Comprehensive View of Disease Characteristics

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1508
Author(s):  
Isabelle Jéru ◽  
Amira Nabil ◽  
Gehad El-Makkawy ◽  
Olivier Lascols ◽  
Corinne Vigouroux ◽  
...  
Keyword(s):  
Phenotypic Variability ◽  
Genetic Disorders ◽  
Autosomal Recessive Disorder ◽  
Missense Variant ◽  
Compound Heterozygous ◽  
Partial Lipodystrophy ◽  
Mandibular Hypoplasia ◽  
Pathogenic Variants ◽  
Compound Heterozygous Variants ◽  
Mandibuloacral Dysplasia

Pathogenic variants in the LMNA gene cause a group of heterogeneous genetic disorders, called laminopathies. In particular, homozygous or compound heterozygous variants in LMNA have been associated with “mandibuloacral dysplasia type A” (MADA), an autosomal recessive disorder, characterized by mandibular hypoplasia, growth retardation mainly postnatal, pigmentary skin changes, progressive osteolysis of the distal phalanges and/or clavicles, and partial lipodystrophy. The detailed characteristics of this multisystemic disease have yet to be specified due to its rarity and the limited number of cases described. Here, we report three unrelated Egyptian patients with variable severity of MAD features. Next-generation sequencing using a gene panel revealed a homozygous c.1580G>A-p.Arg527His missense variant in LMNA exon 9 in an affected individual with a typical MADA phenotype. Another homozygous c.1580G>T-p.Arg527Leu variant affecting the same amino acid was identified in two additional patients, who both presented with severe manifestations very early in life. We combined our observations together with data from all MADA cases reported in the literature to get a clearer picture of the phenotypic variability in this disease. This work raises the number of reported MADA families, argues for the presence of the founder effect in Egypt, and strengthens genotype–phenotype correlations.

scholarly journals New Insights on the Genetic Basis Underlying SHILCA Syndrome: Characterization of the NMNAT1 Pathological Alterations Due to Compound Heterozygous Mutations and Identification of a Novel Alternative Isoform

2021 ◽  
Vol 22 (5) ◽  
pp. 2262
Author(s):  
Víctor Abad-Morales ◽  
Ana Wert ◽  
María Ángeles Ruiz Gómez ◽  
Rafael Navarro ◽  
Esther Pomares
Keyword(s):  
Clinical Manifestations ◽  
Autosomal Recessive Disorder ◽  
Severe Form ◽  
Compound Heterozygous ◽  
Healthy Human ◽  
Systemic Involvement ◽  
Pathogenic Variants ◽  
Nicotinamide Mononucleotide ◽  
Transcriptional Alterations ◽  
Epiphyseal Dysplasia

This study aims to genetically characterize a two-year-old patient suffering from multiple systemic abnormalities, including skeletal, nervous and developmental involvements and Leber congenital amaurosis (LCA). Genetic screening by next-generation sequencing identified two heterozygous pathogenic variants in nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1) as the molecular cause of the disease: c.439+5G>T and c.299+526_*968dup.This splice variant has never been reported to date, whereas pathogenic duplication has recently been associated with cases displaying an autosomal recessive disorder that includes a severe form of spondylo-epiphyseal dysplasia, sensorineural hearing loss, intellectual disability and LCA (SHILCA), as well as some brain anomalies. Our patient presented clinical manifestations which correlated strongly with this reported syndrome. To further study the possible transcriptional alterations resulting from these mutations, mRNA expression assays were performed in the patient and her father. The obtained results detected aberrant alternative transcripts and unbalanced levels of expression, consistent with severe systemic involvement. Moreover, these analyses also detected a novel NMNAT1 isoform, which is variably expressed in healthy human tissues. Altogether, these findings represent new evidence of the correlation of NMNAT1 and SHILCA syndrome, and provide additional insights into the healthy and pathogenic expression of this gene.

Atypical Clinical Presentation of Persistent Müllerian Duct Syndrome in Siblings

2021 ◽  
pp. 1-6
Author(s):  
Evgenia Globa ◽  
Nataliya Zelinska ◽  
Nina Siryk ◽  
Anu Bashamboo ◽  
Kenneth McElreavey
Keyword(s):  
Genetic Diagnosis ◽  
Autosomal Recessive Disorder ◽  
Normal Male ◽  
Compound Heterozygous ◽  
Mullerian Duct ◽  
Müllerian Duct ◽  
Persistent Müllerian Duct Syndrome ◽  
Persistent Mullerian Duct Syndrome ◽  
Bilateral Cryptorchidism ◽  
Duct Syndrome

Persistent Müllerian duct syndrome (PMDS) is a rare autosomal recessive disorder characterized by the lack of regression of the derivatives of the Müllerian ducts in males. Boys with this condition usually present with unilateral or bilateral cryptorchidism, inguinal hernias, and reproductive disorders with normal male genitalia. Variants in the AMH or AMHR2 genes are responsible for the development of this syndrome. The genetic diagnosis and surgery in PMDS is challenging for both the endocrinologist and the urologist. Here, we describe the management of 2 siblings from 1 family who presented with bilateral cryptorchidism and hypospadias at birth. One child had testis located in the pelvis in the position of normal ovaries, while the other child had testis which were located in the inguinal canals (bilateral inguinal cryptorchidism). Exome sequencing revealed a compound heterozygous variant in the AMHR2 gene c.1388G>A, p.R463H and c.1412G>A p.R471H. To our knowledge, hypospadias has not been described in association with PMDS.

scholarly journals Bi-allelic variants in MTMR5/SBF1 cause Charcot-Marie-Tooth type 4B3 featuring mitochondrial dysfunction

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Beatrice Berti ◽  
Giovanna Longo ◽  
Francesco Mari ◽  
Stefano Doccini ◽  
Ilaria Piccolo ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Mitochondrial Dysfunction ◽  
Early Onset ◽  
Integrated Approach ◽  
Compound Heterozygous ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
Pathogenic Variants ◽  
First Case ◽  
Spine Mri

Abstract Background Charcot-Marie-Tooth disease (CMT) type 4B3 (CMT4B3) is a rare form of genetic neuropathy associated with variants in the MTMR5/SBF1 gene. MTMR5/SBF1 is a pseudophosphatase predicted to regulate endo-lysosomal trafficking in tandem with other MTMRs. Although almost ubiquitously expressed, pathogenic variants primarily impact on the peripheral nervous system, corroborating the involvement of MTMR5/SBF1 and its molecular partners in Schwann cells-mediated myelinization. Case presentation We report a case of severe CMT4B3 characterized by early-onset motor and axonal polyneuropathy in an Italian child in absence of any evidence of brain and spine MRI abnormalities or intellectual disability and with a biochemical profile suggestive of mitochondrial disease. Using an integrated approach combining both NGS gene panels and WES analysis, we identified two novel compound heterozygous missense variants in MTMR5/SBF1 gene, p.R763H (c.2291G > A) and p.G1064E (c.3194G > A). Studies in muscle identified partial defects of oxidative metabolism. Conclusion We describe the first case of an early onset severe polyneuropathy with motor and axonal involvement, due to recessive variants in the MTMR5/SBF1 gene, with no evidence of brain and spine MRI abnormalities, intellectual disability, no clinical and neurophysiological evidences of distal sensory impairment, and rapid neuromuscular deterioration. This report suggests that MTMR5/SBF1 should be considered in cases of infantile-onset CMT with secondary mitochondrial dysfunction.

scholarly journals Prevalent Pathogenic Variants of ATP7B in Chinese Patients with Wilson’s Disease: Geographical Distribution and Founder Effect

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 336
Author(s):  
Guo-Min Yang ◽  
Rou-Min Wang ◽  
Nan Xia ◽  
Zi-Wei Zheng ◽  
Yi Dong ◽  
...  
Keyword(s):  
Geographical Distribution ◽  
Founder Effect ◽  
Wilson’S Disease ◽  
Autosomal Recessive Disorder ◽  
Wilson's Disease ◽  
Chinese Patients ◽  
Mainland Chinese ◽  
Pathogenic Variants ◽  
Specific Distribution ◽  
The Common

Wilson’s disease (WD) is an autosomal recessive disorder caused by ATP7B pathogenic variants. This study aimed to show the geographical distribution and haplotype spectrum of three prevalent pathogenic variants (p.R778L, p.P992L, p.T935M) in mainland Chinese population and clarify whether the founder effect may account for their origins. We firstly summarized the frequency and geographical distribution of p.R778L, p.P992L and p.T935M in 715 WD patients. Then, to construct haplotypes associated with the three variants, Sanger sequencing and microsatellite typing at three dinucleotide-repeat markers (D13S314, D13S301, D13S316) flanking the ATP7B gene were performed in 102 WD families. An obvious regional-specific distribution feature was found in p.T935M. Linkage disequilibrium at the three markers was shown in all the three variants and we found the common haplotypes specific for p.R778L, p.P992L and p.T935M respectively, represented successively by 10-7-7, 10-9-5 and 12-4-8, which all exhibited great significance vs. the control chromosomes (p < 0.01). Meanwhile, haplotypes for the three variants differed from the studies in other regions to some extent. The common haplotypes we found indicate that three prevalent pathogenic variants emerge due to the founder effect. Furthermore, the study contributes to expand our knowledge of the genetic diversity of WD from a cross-regional perspective.

Molecular Analysis of the CYP11B2 Gene in 62 Patients with Hypoaldosteronism Due to Aldosterone Synthase Deficiency

2020 ◽  
Vol 106 (1) ◽  
pp. e182-e191
Author(s):  
Christina Merakou ◽  
Irene Fylaktou ◽  
Amalia Sertedaki ◽  
Maria Dracopoulou ◽  
Antonis Voutetakis ◽  
...  
Keyword(s):  
Gene Sequencing ◽  
Failure To Thrive ◽  
In Silico Analysis ◽  
Autosomal Recessive Disorder ◽  
Molecular Study ◽  
Aldosterone Synthase ◽  
Salt Wasting ◽  
Pathogenic Variants ◽  
Novel Variants ◽  
Aldosterone Synthase Deficiency

Abstract Context Isolated congenital hypoaldosteronism presents in early infancy with symptoms including vomiting, severe dehydration, salt wasting, and failure to thrive. The main causes of this rare autosomal recessive disorder is pathogenic variants of the CYP11B2 gene leading to aldosterone synthase deficiency. Objective To investigate the presence of CYP11B2 pathogenic variants in a cohort of patients with a clinical, biochemical, and hormonal profile suggestive of aldosterone synthase deficiency. Design Clinical and molecular study. Setting Tertiary academic Children’s Hospital, Center for Rare Pediatric Endocrine Diseases. Patients and Methods Sixty-two patients (56 unrelated patients and 6 siblings), with hypoaldosteronism and their parents, underwent CYP11B2 gene sequencing after its selective amplification against the highly homologous CYP11B1 gene. In silico analysis of the identified novel variants was carried out to evaluate protein stability and potential pathogenicity. Results CYP11B2 gene sequencing revealed that 62 patients carried a total of 12 different pathogenic CYP11B2 gene variants, 6 of which are novel. Importantly, 96% of the 56 patients carried the previously reported p.T185I variant either in homozygosity or in compound heterozygosity with another variant. The 6 novel variants detected were: p.M1I, p.V129M, p.R141Q, p.A165T, p.R448C, and the donor splice site variant of intron 8, c.1398 + 1G &gt; A. Conclusion Molecular diagnosis was achieved in 62 patients with aldosterone synthase deficiency, the largest cohort thus far reported. Six novel genetic variants were identified as possibly pathogenic, extending the spectrum of reported molecular defects of the CYP11B2 gene.

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 Rare Variants in Autophagy and Non-Autophagy Genes in Late-Onset Pompe Disease: Suggestions of Their Disease-Modifying Role in Two Italian Families

2021 ◽  
Vol 22 (7) ◽  
pp. 3625
Author(s):  
Filomena Napolitano ◽  
Giorgia Bruno ◽  
Chiara Terracciano ◽  
Giuseppina Franzese ◽  
Nicole Piera Palomba ◽  
...  
Keyword(s):  
Pompe Disease ◽  
Rare Variants ◽  
Clinical Symptoms ◽  
Late Onset ◽  
Respiratory Muscles ◽  
Autosomal Recessive Disorder ◽  
Compound Heterozygous ◽  
Enzyme Replacement ◽  
Whole Exome ◽  
Clinical Pictures

Pompe disease is an autosomal recessive disorder caused by a deficiency in the enzyme acid alpha-glucosidase. The late-onset form of Pompe disease (LOPD) is characterized by a slowly progressing proximal muscle weakness, often involving respiratory muscles. In LOPD, the levels of GAA enzyme activity and the severity of the clinical pictures may be highly variable among individuals, even in those who harbour the same combination of GAA mutations. The result is an unpredictable genotype–phenotype correlation. The purpose of this study was to identify the genetic factors responsible for the progression, severity and drug response in LOPD. We report here on a detailed clinical, morphological and genetic study, including a whole exome sequencing (WES) analysis of 11 adult LOPD siblings belonging to two Italian families carrying compound heterozygous GAA mutations. We disclosed a heterogeneous pattern of myopathic impairment, associated, among others, with cardiac defects, intracranial vessels abnormality, osteoporosis, vitamin D deficiency, obesity and adverse response to enzyme replacement therapy (ERT). We identified deleterious variants in the genes involved in autophagy, immunity and bone metabolism, which contributed to the severity of the clinical symptoms observed in the LOPD patients. This study emphasizes the multisystem nature of LOPD and highlights the polygenic nature of the complex phenotype disclosed in these patients.

scholarly journals Allele frequency of variants reported to cause adenine phosphoribosyltransferase deficiency

2021 ◽  
Author(s):  
Hrafnhildur L. Runolfsdottir ◽  
John A. Sayer ◽  
Olafur S. Indridason ◽  
Vidar O. Edvardsson ◽  
Brynjar O. Jensson ◽  
...  
Keyword(s):  
Allele Frequency ◽  
Autosomal Recessive Disorder ◽  
European Population ◽  
Adenine Phosphoribosyltransferase ◽  
Genomic Databases ◽  
Pathogenic Variants ◽  
Adenine Phosphoribosyltransferase Deficiency ◽  
Variation Database ◽  
The Uk ◽  
Aprt Deficiency

AbstractAdenine phosphoribosyltransferase deficiency is a rare, autosomal recessive disorder of purine metabolism that causes nephrolithiasis and progressive chronic kidney disease. The small number of reported cases indicates an extremely low prevalence, although it has been suggested that missed diagnoses may play a role. We assessed the prevalence of APRT deficiency based on the frequency of causally-related APRT sequence variants in a diverse set of large genomic databases. A thorough search was carried out for all APRT variants that have been confirmed as pathogenic under recessive mode of inheritance, and the frequency of the identified variants examined in six population genomic databases: the deCODE genetics database, the UK Biobank, the 100,000 Genomes Project, the Genome Aggregation Database, the Human Genetic Variation Database and the Korean Variant Archive. The estimated frequency of homozygous genotypes was calculated using the Hardy-Weinberg equation. Sixty-two pathogenic APRT variants were identified, including six novel variants. Most common were the missense variants c.407T>C (p.(Met136Thr)) in Japan and c.194A>T (p.(Asp65Val)) in Iceland, as well as the splice-site variant c.400 + 2dup (p.(Ala108Glufs*3)) in the European population. Twenty-nine variants were detected in at least one of the six genomic databases. The highest cumulative minor allele frequency (cMAF) of pathogenic variants outside of Japan and Iceland was observed in the Irish population (0.2%), though no APRT deficiency cases have been reported in Ireland. The large number of cases in Japan and Iceland is consistent with a founder effect in these populations. There is no evidence for widespread underdiagnosis based on the current analysis.

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