Several LSDs (mucolipidosis types IV, IIIA [pseudo-Hurler polydystrophy], and II [I-cell disease], late infantile neuronal ceroid lipifuscinosis [CLN2], mucopolysaccharidosis VI, and GM1 gangliosidosis) also display mitochondrial abnormalities, including replacement of the extended tubular mitochondrial network with high numbers of relatively rounded depolarized mitochondria1. This evidence concerns the gene TPP1 and mucolipidosis type III, alpha/beta.