SUCLG1-related MDDS 9 (encephalomyopathic type with methylmalonic aciduria, OMIM #245400) and SUCLA2-related MDDS 5 (encephalomyopathic type with or without methylmalonic aciduria, OMIM #612073) are rare subtypes of MDDS caused by biallelic pathogenic variations in the SUCLG1 and SUCLA2 genes. The gene discussed is SUCLA2; the disease is Methylmalonic aciduria.