المؤلفون: Jonathan Shintaku, Wolfgang M. Pernice, Wafaa Eyaid, Jeevan B. GC, Zuben P. Brown, Marti Juanola-Falgarona, Javier Torres-Torronteras, Ewen W. Sommerville, Debby M.E.I. Hellebrekers, Emma L. Blakely, Alan Donaldson, Ingrid van de Laar, Cheng-Shiun Leu, Ramon Marti, Joachim Frank, Kurenai Tanji, David A. Koolen, Richard J. Rodenburg, Patrick F. Chinnery, H.J.M. Smeets, Gráinne S. Gorman, Penelope E. Bonnen, Robert W. Taylor, Michio Hirano

المصدر: The Journal of Clinical Investigation, Vol 132, Iss 13 (2022)

مصطلحات موضوعية: Genetics, Medicine

الوصف: Mitochondrial DNA (mtDNA) depletion/deletions syndromes (MDDS) encompass a clinically and etiologically heterogenous group of mitochondrial disorders caused by impaired mtDNA maintenance. Among the most frequent causes of MDDS are defects in nucleoside/nucleotide metabolism, which is critical for synthesis and homeostasis of the deoxynucleoside triphosphate (dNTP) substrates of mtDNA replication. A central enzyme for generating dNTPs is ribonucleotide reductase, a critical mediator of de novo nucleotide synthesis composed of catalytic RRM1 subunits in complex with RRM2 or p53R2. Here, we report 5 probands from 4 families who presented with ptosis and ophthalmoplegia as well as other clinical manifestations and multiple mtDNA deletions in muscle. We identified 3 RRM1 loss-of-function variants, including a dominant catalytic site variant (NP_001024.1: p.N427K) and 2 homozygous recessive variants at p.R381, which has evolutionarily conserved interactions with the specificity site. Atomistic molecular dynamics simulations indicate mechanisms by which RRM1 variants affect protein structure. Cultured primary skin fibroblasts of probands manifested mtDNA depletion under cycling conditions, indicating impaired de novo nucleotide synthesis. Fibroblasts also exhibited aberrant nucleoside diphosphate and dNTP pools and mtDNA ribonucleotide incorporation. Our data reveal that primary RRM1 deficiency and, by extension, impaired de novo nucleotide synthesis are causes of MDDS.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1558-8238Test

الوصول الحر: https://doaj.org/article/c33cc000db5c486fac28f774f3298015Test

المؤلفون: Hannie C. W. Douben, Mark Nellist, Leontine van Unen, Peter Elfferich, Esmee Kasteleijn, Marianne Hoogeveen‐Westerveld, Jesse Louwen, Monique van Veghel‐Plandsoen, Walter de Valk, Jasper J. Saris, Femke Hendriks, Esther Korpershoek, Lies H. Hoefsloot, Margreethe van Vliet, Yolande van Bever, Ingrid van de Laar, Emmelien Aten, Augusta M. A. Lachmeijer, Walter Taal, Lisa van den Bersselaar, Juliette Schuurmans, Rianne Oostenbrink, Rick van Minkelen, Yvette van Ierland, Tjakko J. van Ham

المساهمون: Clinical Genetics, Erasmus MC other, Pathology, Neurology, Pediatrics

المصدر: Human Mutation, 43(12), 2130-2140. Wiley-Liss Inc.
Human Mutation: Variation, Informatics and Disease, 43(12), 2130-2140. WILEY-HINDAWI

مصطلحات موضوعية: Neurofibromatosis 1, Neurofibromin 1, RNA Splicing, RNA-sequencing, DNA, Fibroblasts, mRNA splicing, neurofibromatosis type 1, molecular diagnostics, noncoding variants, Mutation, Genetics, Humans, Genetics (clinical), exon skipping

الوصف: Neurofibromatosis type 1 (NF1) is caused by inactivating mutations in NF1. Due to the size, complexity, and high mutation rate at the NF1 locus, the identification of causative variants can be challenging. To obtain a molecular diagnosis in 15 individuals meeting diagnostic criteria for NF1, we performed transcriptome analysis (RNA-seq) on RNA obtained from cultured skin fibroblasts. In each case, routine molecular DNA diagnostics had failed to identify a disease-causing variant in NF1. A pathogenic variant or abnormal mRNA splicing was identified in 13 cases: 6 deep intronic variants and 2 transposon insertions causing noncanonical splicing, 3 postzygotic changes, 1 branch point mutation and, in 1 case, abnormal splicing for which the responsible DNA change remains to be identified. These findings helped resolve the molecular findings for an additional 17 individuals in multiple families with NF1, demonstrating the utility of skin-fibroblast-based transcriptome analysis for molecular diagnostics. RNA-seq improves mutation detection in NF1 and provides a powerful complementary approach to DNA-based methods. Importantly, our approach is applicable to other genetic disorders, particularly those caused by a wide variety of variants in a limited number of genes and specifically for individuals in whom routine molecular DNA diagnostics did not identify the causative variant.

وصف الملف: application/pdf

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dd3d626b36d5a4ec4586b987251a1250Test
https://hdl.handle.net/1887/3563778Test