Human COQ4 deficiency: delineating the clinical, metabolic and neuroimaging phenotypes

Laugwitz L., Seibt A., Herebian D., Peralta S., Kienzle I., Buchert R., ...More

JOURNAL OF MEDICAL GENETICS, vol.59, no.9, pp.878-887, 2022 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 59 Issue: 9
  • Publication Date: 2022
  • Doi Number: 10.1136/jmedgenet-2021-107729
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, EMBASE, MEDLINE
  • Page Numbers: pp.878-887
  • Keywords: nervous system diseases, pediatrics, epilepsy, early diagnosis, PEDIATRIC MITOCHONDRIAL DISEASE, COENZYME-Q, BIOSYNTHESIS, MUTATIONS, ATAXIA, MUSCLE
  • Erciyes University Affiliated: Yes


Background Human coenzyme Q4 (COQ4) is essential for coenzyme Q(10) (CoQ(10)) biosynthesis. Pathogenic variants in COQ4 cause childhood-onset neurodegeneration. We aimed to delineate the clinical spectrum and the cellular consequences of COQ4 deficiency. Methods Clinical course and neuroradiological findings in a large cohort of paediatric patients with COQ4 deficiency were analysed. Functional studies in patient-derived cell lines were performed. Results We characterised 44 individuals from 36 families with COQ4 deficiency (16 newly described). A total of 23 different variants were identified, including four novel variants in COQ4. Correlation analyses of clinical and neuroimaging findings revealed three disease patterns: type 1: early-onset phenotype with neonatal brain anomalies and epileptic encephalopathy; type 2: intermediate phenotype with distinct stroke-like lesions; and type 3: moderate phenotype with non-specific brain pathology and a stable disease course. The functional relevance of COQ4 variants was supported by in vitro studies using patient-derived fibroblast lines. Experiments revealed significantly decreased COQ4 protein levels, reduced levels of cellular CoQ(10) and elevated levels of the metabolic intermediate 6-demethoxyubiquinone. Conclusion Our study describes the heterogeneous clinical presentation of COQ4 deficiency and identifies phenotypic subtypes. Cell-based studies support the pathogenic characteristics of COQ4 variants. Due to the insufficient clinical response to oral CoQ(10) supplementation, alternative treatment strategies are warranted.