LAMP2 and dentin dysplasia: DD is an X-linked dominant disorder caused by the deficiency of lysosome-associated membrane protein 2 (LAMP2).4 DD patients typically show hypertrophic cardiomyopathy, muscle weakness and mental retardation.5 LAMP2 is mainly localized in the limiting membranes of lysosomes and late endosomes and, in small amounts, in early endosomal and plasma membrane.