Further phenotypic heterogeneity of CoQ10 deficiency associated with Steroid Resistant Nephrotic Syndrome and novel COQ2 and COQ6 variants.

We descripe three patients with SRNS associated with pathogentic changes in two CoQ pathway genes: one novel homozygous COQ2 variant was identified in two cousins with adolescent-onset SRNS and mild neurological symptoms (Family 1); and one novel COQ6 variant was found in a child with early onset SRNS without deafness and neurological involvement (Family 2). (A, B) : families (C) : Sanger sequencing showing COQ2 change: NM_015697.7: c.1169G>C; NP_056512.5; p.Gly390Ala (c.1019G>C; p.Gly340Ala, according to KU877220 GenBank sequence) (D) : Sanger sequencing showing COQ6 change: NM_182476.2:c.782C>T; NP_872282.1:p.Pro261Leu. (E, F): Functional complementation in yeast. Serial dilutions of ΔCOQ2 and ΔCOQ6 yeast transformed with wild-type, the empty vector and the mutant alleles; complex II+III (C.II+C.III) and citrate synthase (CS) activities.