Citine-acylcitine translocase (CACT) deficiency (OMIM 212138) is an autosomal recessive disease caused by mutations of the SLC25A20 gene [solute carrier family 25 (citine/acylcitine translocase), member 20]. The gene has an open reading frame of 903 bp,1 mapped to chromosome 3p21.31 by in situ hybridization,2 and encodes a protein having three repeated homologous domains, each about 100 amino acids in length-a characteristic feature of mitochondrial transport proteins.3,4 CACT is essential in long-chain fatty acid oxidation because CACT is located in the inner side of the inner mitochondrial membrane, shuttling long-chain acylcitines in the intermembranous space against citine in the mitochondrial matrix. The first patient with CACT deficiency reported in the United States,5 and the first patient reported in the United Kingdom6 are both of mixed ethnicity with one of the parents being Chinese. Intriguingly, there is no single case of CACT deficiency reported in Chinese populations, suggesting that this disease may be underdiagnosed in Chinese populations. In this study, we have confirmed that CACT deficiency can be a cause of sudden neonatal death in Chinese.