[Molecular pathology of neurogenetic diseases].

Recently, techniques of molecular biology have been widely applied to child neurology, and a new aspect of the pathogenesis of neurogenetic diseases has been revealed. In this article, recent results of molecular analysis in my laboratory were briefly reviewed on hereditary beta-galactosidase deficiency. After cDNA cloning, a number of gene mutations have been identified; mainly missense mutations, such as single-base substitution, duplication, insertion, and splice site mutation. A clear phenotype-genotype correlation was established for some mutations specific to the late-onset forms of the disease. Intracellular events of mutant proteins expressed by these mutant genes were heterogeneous, and expected to be closely connected to the pathogenesis of each phenotype. On the basis of these data, a unified clinical classification was proposed for GM1-gangliosidosis and Morquio B disease, together with a new concept of "beta-galactosidosis" for the diseases with beta-galactosidase gene mutations.