Chapter 27 - Neuroectodermal Melanolysosomal Disease

Abstract

This chapter describes neuroectodermal melanolysosomal disease (NEMLD). NEMLD is characterized by abnormal hair color, severe dysfunction of the central nervous system—profound mental, developmental, and behavioral retardation—abnormal intracytoplasmic inclusions in all tissues studied, and abnormally formed melanosomes. The condition appears to be caused by the pleiotropic effects of an autosomal recessive gene in its homozygous state, producing various phenotypic effects in different tissues. The unusual hair color probably results from the melanocytes in the hair bulb producing melanin in the presence of the different substrates. The color of the hair is probably produced by two factors: (1) the distribution of the melanosomes in the hair shaft, and (2) the diffraction, refraction, and absorption of light by both the pigment granules and the hair matrix. Abnormalities of the dopaminergic pathway are known to be associated with an abnormally functioning central nervous system. In NEMLD, the hypomelanized melanosomes in the skin, the lysosomal inclusions in the fibroblasts, and the lymphocytes and bone marrow cells can be considered authophenes. No specific treatment is available for NEMLD. The infants and children require the specialized care appropriate for children with profound mental retardation and cerebral palsy.