Rare Association of Mucolipidosis III alpha/beta with Dilated Cardiomyopathy

Mucolipidosis III alpha/beta (ML III alpha/beta) is an autosomal recessive lysosomal storage disorder caused by N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase) deficiency. It is characterized by coarse facial features, developmental delay, short stature, and skeletal deformities. Its cardiovascular symptoms include valvular thickening or hypertrophic cardiomyopathy. A 32-year-old female patient received heart transplantation due to end-stage heart failure caused by dilated cardiomyopathy (DCM). We performed whole exome sequencing to determine the etiology of DCM and/or skeletal deformities. The test revealed c.2715+1G>A and c.3173C>G mutations in the GNPTAB gene encoding the alpha and beta subunits of GlcNAc-phosphotransferase. Finally, she was diagnosed with ML III alpha/beta. This report describes a rare case of ML III alpha/beta associated with DCM. Our findings expand the clinical spectrum of ML III alpha/beta.