title: Characterization of CoQ₁₀ biosynthesis in fibroblasts of patients with primary and secondary CoQ₁₀ deficiency.
abstract: Primary coenzyme Q₁₀ (CoQ₁₀) deficiencies are associated with mutations in genes encoding enzymes important for its biosynthesis and patients are responsive to CoQ₁₀ supplementation. Early treatment allows better prognosis of the disease and therefore, early diagnosis is desirable. The complex phenotype and genotype and the frequent secondary CoQ₁₀ deficiencies make it difficult to achieve a definitive diagnosis by direct quantification of CoQ₁₀. We developed a non-radioactive methodology for the quantification of CoQ₁₀ biosynthesis in fibroblasts that allows the identification of primary deficiencies. Fibroblasts were incubated 72 h with 28 μmol/L (2)H₃-mevalonate or 1.65 mmol/L (13)C₆-p-hydroxybenzoate. The newly synthesized (2)H₃- and (13)C₆- labelled CoQ₁₀ were analysed by high performance liquid chromatography-tandem mass spectrometry. The mean and the reference range for (13)C₆-CoQ₁₀ and (2)H₃-CoQ₁₀ biosynthesis were 0.97 (0.83-1.1) and 0.13 (0.09-0.17) nmol/Unit of citrate synthase, respectively. We validated the methodology through the study of one patient with COQ2 mutations and six patients with CoQ₁₀ deficiency secondary to other inborn errors of metabolism. Afterwards we investigated 16 patients' fibroblasts and nine showed decreased CoQ₁₀ biosynthesis. Therefore, the next step is to study the COQ genes in order to reach a definitive diagnosis in these nine patients. In the patients with normal rates the deficiency is probably secondary. In conclusion, we have developed a non-invasive non-radioactive method suitable for the detection of defects in CoQ₁₀ biosynthesis, which offers a good tool for the stratification of patients with these treatable mitochondrial diseases.
authors.affiliation: Secció d'Errors Congènits del Metabolisme-IBC, Servei de Bioquímica i Genètica Molecular, Hospital Clínic, CIBERER, Edifici Helios III, planta baixa, C/Mejía Lequerica s/n, 08028, Barcelona, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Buján
authors.forename: Angela
authors.initials: A
authors.lastname: Arias
authors.forename: Raquel
authors.initials: R
authors.lastname: Montero
authors.forename: Judit
authors.initials: J
authors.lastname: García-Villoria
authors.forename: Willy
authors.initials: W
authors.lastname: Lissens
authors.forename: Sara
authors.initials: S
authors.lastname: Seneca
authors.forename: Carmen
authors.initials: C
authors.lastname: Espinós
authors.forename: Plácido
authors.initials: P
authors.lastname: Navas
authors.forename: Linda
authors.initials: L
authors.lastname: De Meirleir
authors.forename: Rafael
authors.initials: R
authors.lastname: Artuch
authors.forename: Paz
authors.initials: P
authors.lastname: Briones
authors.forename: Antonia
authors.initials: A
authors.lastname: Ribes
mesh_terms: D001259:Ataxia / Q000175:diagnosis* / Q000378:metabolism*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D005838:Genotype; D006801:Humans; D028361:Mitochondrial Diseases / Q000175:diagnosis* / Q000378:metabolism*; D025202:Molecular Diagnostic Techniques; D018908:Muscle Weakness / Q000175:diagnosis* / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D012016:Reference Values; D015203:Reproducibility of Results; D012867:Skin / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000172:deficiency* / Q000378:metabolism
chemical_list: D014451:Ubiquinone; D002950:Citrate (si)-Synthase; C024989:coenzyme Q10