@article {1022, title = {POLRMT mutations impair mitochondrial transcription causing neurological disease.}, journal = {Nat Commun}, volume = {12}, year = {2021}, month = {2021 02 18}, pages = {1135}, abstract = {

While >300 disease-causing variants have been identified in the mitochondrial DNA (mtDNA) polymerase γ, no mitochondrial phenotypes have been associated with POLRMT, the RNA polymerase responsible for transcription of the mitochondrial genome. Here, we characterise the clinical and molecular nature of POLRMT variants in eight individuals from seven unrelated families. Patients present with global developmental delay, hypotonia, short stature, and speech/intellectual disability in childhood; one subject displayed an indolent progressive external ophthalmoplegia phenotype. Massive parallel sequencing of all subjects identifies recessive and dominant variants in the POLRMT gene. Patient fibroblasts have a defect in mitochondrial mRNA synthesis, but no mtDNA deletions or copy number abnormalities. The in vitro characterisation of the recombinant POLRMT mutants reveals variable, but deleterious effects on mitochondrial transcription. Together, our in vivo and in vitro functional studies of POLRMT variants establish defective mitochondrial transcription as an important disease mechanism.

}, keywords = {Adolescent, Adult, Child, DNA, Mitochondrial, DNA-Directed RNA Polymerases, Female, Fibroblasts, Humans, Infant, Male, Mitochondria, Mutation, Nervous System Diseases, Oxidative Phosphorylation, Pedigree, Protein Domains, Protein Subunits, RNA, Messenger, Transcription, Genetic, Young Adult}, issn = {2041-1723}, doi = {10.1038/s41467-021-21279-0}, author = {Ol{\'a}hov{\'a}, Monika and Peter, Bradley and Szilagyi, Zsolt and Diaz-Maldonado, Hector and Singh, Meenakshi and Sommerville, Ewen W and Blakely, Emma L and Collier, Jack J and Hoberg, Emily and Str{\'a}neck{\'y}, Viktor and Hartmannov{\'a}, Hana and Bleyer, Anthony J and McBride, Kim L and Bowden, Sasigarn A and Korandov{\'a}, Zuzana and Pecinov{\'a}, Alena and Ropers, Hans-Hilger and Kahrizi, Kimia and Najmabadi, Hossein and Tarnopolsky, Mark A and Brady, Lauren I and Weaver, K Nicole and Prada, Carlos E and {\~O}unap, Katrin and Wojcik, Monica H and Pajusalu, Sander and Syeda, Safoora B and Pais, Lynn and Estrella, Elicia A and Bruels, Christine C and Kunkel, Louis M and Kang, Peter B and Bonnen, Penelope E and Mr{\'a}{\v c}ek, Tom{\'a}{\v s} and Kmoch, Stanislav and Gorman, Gr{\'a}inne S and Falkenberg, Maria and Gustafsson, Claes M and Taylor, Robert W} } @article {90, title = {Recurrent Muscle Weakness with Rhabdomyolysis, Metabolic Crises, and Cardiac Arrhythmia Due to Bi-allelic TANGO2 Mutations.}, journal = {Am J Hum Genet}, volume = {98}, year = {2016}, month = {2016 Feb 04}, pages = {347-57}, abstract = {

The underlying genetic etiology of rhabdomyolysis remains elusive in a significant fraction of individuals presenting with recurrent metabolic crises and muscle weakness. Using exome sequencing, we identified bi-allelic mutations in TANGO2 encoding transport and Golgi organization 2 homolog (Drosophila) in 12 subjects with episodic rhabdomyolysis, hypoglycemia, hyperammonemia, and susceptibility to life-threatening cardiac tachyarrhythmias. A recurrent homozygous c.460G>A (p.Gly154Arg) mutation was found in four unrelated individuals of Hispanic/Latino origin, and a homozygous \~{}34 kb deletion affecting exons 3-9 was observed in two families of European ancestry. One individual of mixed Hispanic/European descent was found to be compound heterozygous for c.460G>A (p.Gly154Arg) and the deletion of exons 3-9. Additionally, a homozygous exons 4-6 deletion was identified in a consanguineous Middle Eastern Arab family. No homozygotes have been reported for these changes in control databases. Fibroblasts derived from a subject with the recurrent c.460G>A (p.Gly154Arg) mutation showed evidence of increased endoplasmic reticulum stress and a reduction in Golgi volume density in comparison to control. Our results show that the c.460G>A (p.Gly154Arg) mutation and the exons 3-9 heterozygous deletion in TANGO2 are recurrent pathogenic alleles present in the Latino/Hispanic and European populations, respectively, causing considerable morbidity in the homozygotes in these populations.

}, keywords = {Alleles, Arabs, Arrhythmias, Cardiac, Base Sequence, Child, Child, Preschool, Endoplasmic Reticulum Stress, European Continental Ancestry Group, Exome, Exons, Female, Gene Deletion, Golgi Apparatus, Hispanic Americans, Homozygote, Humans, Infant, Male, Molecular Sequence Data, Muscle Weakness, Pedigree, Rhabdomyolysis}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.12.008}, author = {Lalani, Seema R and Liu, Pengfei and Rosenfeld, Jill A and Watkin, Levi B and Chiang, Theodore and Leduc, Magalie S and Zhu, Wenmiao and Ding, Yan and Pan, Shujuan and Vetrini, Francesco and Miyake, Christina Y and Shinawi, Marwan and Gambin, Tomasz and Eldomery, Mohammad K and Akdemir, Zeynep Hande Coban and Emrick, Lisa and Wilnai, Yael and Schelley, Susan and Koenig, Mary Kay and Memon, Nada and Farach, Laura S and Coe, Bradley P and Azamian, Mahshid and Hernandez, Patricia and Zapata, Gladys and Jhangiani, Shalini N and Muzny, Donna M and Lotze, Timothy and Clark, Gary and Wilfong, Angus and Northrup, Hope and Adesina, Adekunle and Bacino, Carlos A and Scaglia, Fernando and Bonnen, Penelope E and Crosson, Jane and Duis, Jessica and Maegawa, Gustavo H B and Coman, David and Inwood, Anita and McGill, Jim and Boerwinkle, Eric and Graham, Brett and Beaudet, Art and Eng, Christine M and Hanchard, Neil A and Xia, Fan and Orange, Jordan S and Gibbs, Richard A and Lupski, James R and Yang, Yaping} } @article {158, title = {Successful diagnosis of HIBCH deficiency from exome sequencing and positive retrospective analysis of newborn screening cards in two siblings presenting with Leigh{\textquoteright}s disease.}, journal = {Mol Genet Metab}, volume = {115}, year = {2015}, month = {2015 Aug}, pages = {161-7}, abstract = {

PURPOSE: 3-Hydroxyisobutryl-CoA hydrolase (HIBCH) deficiency is a rare disorder of valine metabolism. We present a family with the oldest reported subjects with HIBCH deficiency and provide support that HIBCH deficiency should be included in the differential for elevated hydroxy-C4-carnitine in newborn screening (NBS).

METHODS: Whole exome sequencing (WES) was performed on one affected sibling. HIBCH enzymatic activity was measured in patient fibroblasts. Acylcarnitines were measured by electrospray ionization tandem mass spectrometry (ESI-MS/MS). Disease incidence was estimated using a cohort of 61,434 individuals.

RESULTS: Two siblings presented with infantile-onset, progressive neurodegenerative disease. WES identified a novel homozygous variant in HIBCH c.196C>T; p.Arg66Trp. HIBCH enzymatic activity was significantly reduced in patients{\textquoteright} fibroblasts. Acylcarnitine analysis showed elevated hydroxy-C4-carnitine in blood spots of both affected siblings, including in their NBS cards, while plasma acylcarnitines were normal. Estimates show HIBCH deficiency incidence as high as 1 in ~130,000 individuals.

CONCLUSION: We describe a novel family with HIBCH deficiency at the biochemical, enzymatic and molecular level. Disease incidence estimates indicate HIBCH deficiency may be under-diagnosed. This together with the elevated hydroxy-C4-carnitine found in the retrospective analysis of our patient{\textquoteright}s NBS cards suggests that this disorder could be screened for by NBS programs and should be added to the differential diagnosis for elevated hydroxy-C4-carnitine which is already measured in most NBS programs using MS/MS.

}, keywords = {Abnormalities, Multiple, Adolescent, Amino Acid Metabolism, Inborn Errors, Carnitine, Child, Child, Preschool, Cohort Studies, Exome, Female, Fibroblasts, Humans, Infant, Infant, Newborn, Leigh Disease, Male, Mass Spectrometry, Neonatal Screening, Prognosis, Retrospective Studies, Sequence Analysis, DNA, Siblings, Thiolester Hydrolases}, issn = {1096-7206}, doi = {10.1016/j.ymgme.2015.05.008}, author = {Stiles, Ashlee R and Ferdinandusse, Sacha and Besse, Arnaud and Appadurai, Vivek and Leydiker, Karen B and Cambray-Forker, E J and Bonnen, Penelope E and Abdenur, Jose E} } @article {297, title = {TM4SF20 ancestral deletion and susceptibility to a pediatric disorder of early language delay and cerebral white matter hyperintensities.}, journal = {Am J Hum Genet}, volume = {93}, year = {2013}, month = {2013 Aug 08}, pages = {197-210}, abstract = {

White matter hyperintensities (WMHs) of the brain are important markers of aging and small-vessel disease. WMHs are rare in healthy children and, when observed, often occur with comorbid neuroinflammatory or vasculitic processes. Here, we describe a complex 4 kb deletion in 2q36.3 that segregates with early childhood communication disorders and WMH in 15 unrelated families predominantly from Southeast Asia. The premature brain aging phenotype with punctate and multifocal WMHs was observed in ~70\% of young carrier parents who underwent brain MRI. The complex deletion removes the penultimate exon 3 of TM4SF20, a gene encoding a transmembrane protein of unknown function. Minigene analysis showed that the resultant net loss of an exon introduces a premature stop codon, which, in turn, leads to the generation of a stable protein that fails to target to the plasma membrane and accumulates in the cytoplasm. Finally, we report this deletion to be enriched in individuals of Vietnamese Kinh descent, with an allele frequency of about 1\%, embedded in an ancestral haplotype. Our data point to a constellation of early language delay and WMH phenotypes, driven by a likely toxic mechanism of TM4SF20 truncation, and highlight the importance of understanding and managing population-specific low-frequency pathogenic alleles.

}, keywords = {Age of Onset, Aging, Premature, Asian Continental Ancestry Group, Base Sequence, Brain, Child, Child, Preschool, Chromosomes, Human, Pair 2, Exons, Female, Genetic Predisposition to Disease, Humans, Language Development Disorders, Leukoencephalopathies, Magnetic Resonance Imaging, Male, Molecular Sequence Data, Pedigree, Sequence Analysis, DNA, Sequence Deletion, Tetraspanins}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2013.05.027}, author = {Wiszniewski, Wojciech and Hunter, Jill V and Hanchard, Neil A and Willer, Jason R and Shaw, Chad and Tian, Qi and Illner, Anna and Wang, Xueqing and Cheung, Sau W and Patel, Ankita and Campbell, Ian M and Gelowani, Violet and Hixson, Patricia and Ester, Audrey R and Azamian, Mahshid S and Potocki, Lorraine and Zapata, Gladys and Hernandez, Patricia P and Ramocki, Melissa B and Santos-Cortez, Regie L P and Wang, Gao and York, Michele K and Justice, Monica J and Chu, Zili D and Bader, Patricia I and Omo-Griffith, Lisa and Madduri, Nirupama S and Scharer, Gunter and Crawford, Heather P and Yanatatsaneejit, Pattamawadee and Eifert, Anna and Kerr, Jeffery and Bacino, Carlos A and Franklin, Adiaha I A and Goin-Kochel, Robin P and Simpson, Gayle and Immken, LaDonna and Haque, Muhammad E and Stosic, Marija and Williams, Misti D and Morgan, Thomas M and Pruthi, Sumit and Omary, Reed and Boyadjiev, Simeon A and Win, Kay K and Thida, Aye and Hurles, Matthew and Hibberd, Martin Lloyd and Khor, Chiea Chuen and Van Vinh Chau, Nguyen and Gallagher, Thomas E and Mutirangura, Apiwat and Stankiewicz, Pawel and Beaudet, Arthur L and Maletic-Savatic, Mirjana and Rosenfeld, Jill A and Shaffer, Lisa G and Davis, Erica E and Belmont, John W and Dunstan, Sarah and Simmons, Cameron P and Bonnen, Penelope E and Leal, Suzanne M and Katsanis, Nicholas and Lupski, James R and Lalani, Seema R} }