Analysis of Sanfilippo A gene mutations in a large pedigree.

Mucopolysaccharidosis type IIIA, also known as Sanfilippo A disease, results from mutations in the sulfamidase gene. To date, a total of 62 mutations have been described underlying this lysosomal disorder. Expression studies on missense mutations have shown that each alteration was disease-causing and helped to clarify the genotype-phenotype correlation. In this report we describe a large pedigree where the mutations have been identified in two second cousins: one with severe disease (E369K/R433Q) and the other with a mild form of the illness (E369K/P128L). This study places R433Q as a severe mutation underlying Sanfilippo A disease.

Uptake of recombinant iduronate-2-sulfatase into neuronal and glial cells in vitro.

Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is a congenital storage disorder resulting from mutations on the iduronate-2-sulfatase (IDS) gene. The disease shows variable clinical phenotypes from severe to mild with progressive neurological dysfunction. The therapeutic options for treatment of MPS II are limited and currently no specific therapies are available; the problem is further compounded by difficulties in delivering therapeutic agents to the central nervous system (CNS). In this work, as a potential treatment for this disease, the transfer of the recombinant IDS enzyme into brain cells has been studied in vitro. Two different approaches to obtain recombinant IDS have been utilized: production of the recombinant enzyme by a transfected human clone (Bosc 23 cells); production of the recombinant enzyme by adenoviral transduction of neuronal (SK-N-BE) or glial (C6) cells. Our data indicate that the transfected as well as the infected cells produce a large amount of the IDS enzyme, which is efficiently endocytosed into neuronal and glial cells through the mannose 6-phosphate (M6P) receptor system. Somatic gene therapy appears therefore to be suitable to correct IDS deficiency in brain cells.