Novel variant p.(Ala102Thr) in SDHB causes mitochondrial complex II deficiency: Case report and review of the literature

Leigh syndrome is a clinically and radiologically heterogeneous condition with approximately 75 genes, nuclear and mitochondrial, known to be implicated in its pathogenesis. Leigh syndrome due to complex II deficiency constitutes 2% to 7% of these cases. Previously, nine individuals with Leigh syndrome have been reported with pathogenic variants in SDHB, which encodes for the iron–sulfur cluster subunit of mitochondrial respiratory chain complex II. The proband presented with Leigh syndrome. Exome sequencing revealed a homozygous missense variant p.(Ala102Thr) in SDHB. In silico protein modeling of the wild-type and mutant proteins showed potentially decreased protein stability. We hereby report another individual with Leigh syndrome due to SDHB-related mitochondrial complex II deficiency and review the phenotype and genotype associated with this condition.