Dataset Information

Early Onset of Combined Oxidative Phosphorylation Deficiency in Two Chinese Brothers Caused by a Homozygous (Leu275Phe) Mutation in the C1QBP Gene.

ABSTRACT: Mitochondrial diseases constitute a group of heterogeneous hereditary diseases caused by impairments in mitochondrial oxidative phosphorylation and abnormal cellular energy metabolism. C1QBP plays an important role in mitochondrial homeostasis. In this study, clinical, laboratory examinations, 12-lead electrocardiographic, ultrasonic cardiogram, and magnetic resonance imaging data were collected from four members of a Chinese family. Whole exome were amplified and sequenced for the proband. The structure of protein encoded by the mutation was predicted using multiple software programs. The proband was a 14-year old boy with myocardial hypertrophy, exercise intolerance, ptosis, and increased lactate. His 9-year old brother exhibited similar clinical manifestations while the phenomenon of ptosis was not as noticeable as the proband. The onset of this disease was in infancy in both cases. They were born after uneventful pregnancies of five generation blood relative Chinese parents. A homozygous mutation (Leu275Phe) in the C1QBP gene was identified in both brothers in an autosomal recessive inherited pattern. Their parents were heterozygous mutation carriers without clinical manifestations. We demonstrated that a homozygous C1QBP- P.Leu275Phe mutation in an autosomal recessive inherited mode of inheritance caused early onset combined oxidative phosphorylation deficiency 33 (COXPD 33) (OMIM:617713) in two brothers from a Chinese family.

SUBMITTER: Wang J

PROVIDER: S-EPMC7738465 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Early Onset of Combined Oxidative Phosphorylation Deficiency in Two Chinese Brothers Caused by a Homozygous (Leu275Phe) Mutation in the <i>C1QBP</i> Gene.

Wang Jie J Li Huan H Sun Min M Yang Ying Y Yang Qianli Q Liu Bailing B Liu Fang F Hu Wen W Zhang Yanmin Y

Frontiers in pediatrics 20201202

Mitochondrial diseases constitute a group of heterogeneous hereditary diseases caused by impairments in mitochondrial oxidative phosphorylation and abnormal cellular energy metabolism. C1QBP plays an important role in mitochondrial homeostasis. In this study, clinical, laboratory examinations, 12-lead electrocardiographic, ultrasonic cardiogram, and magnetic resonance imaging data were collected from four members of a Chinese family. Whole exome were amplified and sequenced for the proband. The ...[more]

PMID: 33344382

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Project description:BackgroundLeigh syndrome (LS) is a common mitochondrial disease caused by mutations in both mitochondrial and nuclear genes. Isoleucyl-tRNA synthetase 2 (IARS2) encodes mitochondrial isoleucine-tRNA synthetase, and variants in IARS2 have been reported to cause LS. However, the pathogenic mechanism of IARS2 variants is still unclear.MethodsTwo unrelated patients, a 4-year-old boy and a 5-year-old boy diagnosed with LS, were recruited, and detailed clinical data were collected. The DNA of the patients and their parents was isolated from the peripheral blood for the identification of pathogenic variants using next-generation sequencing and Sanger sequencing. The ClustalW program, allele frequency analysis databases (gnomAD and ExAc), and pathogenicity prediction databases (Clinvar, Mutation Taster and PolyPhen2) were used to predict the conservation and pathogenicity of the variants. The gene expression level, oxygen consumption rate (OCR), respiratory chain complex activity, cellular adenosine triphosphate (ATP) production, mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (ROS) levels were measured in patient-derived lymphocytes and IARS2-knockdown HEK293T cells to evaluate the pathogenicity of the variants.ResultsWe reported 2 unrelated Chinese patients manifested with LS who carried biallelic IARS2 variants (c.1_390del and c.2450G > A from a 4-year-old boy, and c.2090G > A and c.2122G > A from a 5-year-old boy), of which c.1_390del and c.2090G > A were novel. Functional studies revealed that the patient-derived lymphocytes carrying c.1_390del and c.2450G > A variants exhibited impaired mitochondrial function due to severe mitochondrial complexes I and III deficiencies, which was also found in IARS2-knockdown HEK293T cells. The compensatory experiments in vitro cell models confirmed the pathogenicity of IARS2 variants since re-expression of wild-type IARS2 rather than mutant IARS2 could rescue complexes I and III deficiency, oxygen consumption, and cellular ATP content in IARS2 knockdown cells.ConclusionOur results not only expand the gene mutation spectrum of LS, but also reveal for the first time the pathogenic mechanism of IARS2 variants due to a combined deficiency of mitochondrial complexes I and III, which is helpful for the clinical diagnosis of IARS2 mutation-related diseases.

Dataset Information

Early Onset of Combined Oxidative Phosphorylation Deficiency in Two Chinese Brothers Caused by a Homozygous (Leu275Phe) Mutation in the C1QBP Gene.

Publications

Early Onset of Combined Oxidative Phosphorylation Deficiency in Two Chinese Brothers Caused by a Homozygous (Leu275Phe) Mutation in the <i>C1QBP</i> Gene.

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