NARS2 and Combined oxidative phosphorylation defect type 24: Combined oxidative phosphorylation deficiency type 24 (COXPD24, OMIM #616239) is an autosomal recessive mitochondrial disorder caused by biallelic pathogenic variants in the NARS2 gene (chromosome 11q14.3), which encodes mitochondrial asparaginyl-tRNA synthetase (1, 2).