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Mitochondrial Complex III Deficiency Caused by a Homozygous UQCRC2 Mutation Presenting with Neonatal‐Onset Recurrent Metabolic Decompensation
Author(s) -
Miyake Noriko,
Yano Shoji,
Sakai Chika,
Hatakeyama Hideyuki,
Matsushima Yuichi,
Shiina Masaaki,
Watanabe Yoriko,
Bartley James,
Abdenur Jose E.,
Wang Raymond Y.,
Chang Richard,
Tsurusaki Yoshinori,
Doi Hiroshi,
Nakashima Mitsuko,
Saitsu Hirotomo,
Ogata Kazuhiro,
Goto Yuichi,
Matsumoto Naomichi
Publication year - 2013
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.22257
Subject(s) - biology , lactic acidosis , missense mutation , mitochondrial disease , compound heterozygosity , mitochondrial dna , genetics , leigh disease , mitochondrial respiratory chain , mutation , mitochondrion , gene , endocrinology
Mitochondrial complex III ( CIII ) deficiency is a relatively rare disease with high clinical and genetic heterogeneity. CIII comprises 11 subunits encoded by one mitochondrial and 10 nuclear genes. Abnormalities of the nuclear genes such as BCS1L and TTC19 encoding mitochondrial assembly factors are well known, but an explanation of the majority of CIII deficiency remains elusive. Here, we report three patients from a consanguineous Mexican family presenting with neonatal onset of hypoglycemia, lactic acidosis, ketosis, and hyperammonemia. We found a homozygous missense mutation in UQCRC2 that encodes mitochondrial ubiquinol–cytochrome c reductase core protein II by whole‐exome sequencing combined with linkage analysis. On the basis of structural modeling, the mutation (p. A rg183 T rp) was predicted to destabilize the hydrophobic core at the subunit interface of the core protein II homodimer. In vitro studies using fibroblasts from the index patient clearly indicated CIII deficiency, as well as impaired assembly of the supercomplex formed from complexes I , III , and IV . This is the first described human disease caused by a core protein abnormality in mitochondrial CIII .