UQCRC2 and lactic acidosis: She experienced recurrent episodes of metabolic decompensation, including hypoglycemia and lactic acidosis, and was found by whole-exome sequencing (WES) to be heterozygous for two novel missense variants in UQCRC2 (c.1189G>A; p.Gly397Arg and c.437T>C; p.Phe146Ser).