A new case of malonyl‐CoA decarboxylase deficiency with mild clinical features

Malonyl‐CoA decarboxylase deficiency is an extremely rare autosomal recessive inborn error of fatty acid metabolism. It usually follows a severe disease course and presents poor prognosis without treatment. Here, we report an affected female juvenile with a mild clinical and biochemical phenotype who mainly featured poor schooling without cardiomyopathy and metabolic acidosis. She was suspected of malonyl‐CoA decarboxylase deficiency due to a 57‐kb deletion in 16q23.3 encompassing the MLCYD gene revealed by chromosome microarray. Malonyl‐CoA decarboxylase deficiency was then confirmed by acylcarnitine analysis and organic acid analysis. Real‐time PCR analysis of the patient revealed the first three exon deletion of the MLYCD gene, which was maternally inherited. DNA sequencing of the MLYCD gene of the patient identified a novel heterozygous mutation (c.911G>A, p.G304E) in exon 4 that was paternally inherited. The patient urine malonic acid dissolved and had a better school record in 6 month after initiation of fat‐limited diet. At 1 year post treatment, the blood malonylcarnitine level decreased remarkably. Our result expands the phenotype of malonyl‐CoA decarboxylase deficiency and suggests attentions should be paid to the mild form of disorders, for example, malonyl‐CoA decarboxylase deficiency, which usually present a severe disease course. © 2016 Wiley Periodicals, Inc.