Clinical, enzymatic, and molecular characterisation of a Portuguese family with a chronic form of GM2-gangliosidosis B 1 variant

Abstract

Mutations in the hexosaminidase A gene (HEXA) causing the Bi variant of Gm2gangliosidosis result in the presence of a mutant enzyme protein with a catalytically defective u subunit. A rare and panethnically distributed mutation, transition G533A (Argl78His), is known to be a common allele among Porlaiguese patients with the subacute phenotype. We now report the presence of an Argl7SHis allele in three Portuguese sibs with a chronic form of the disease, who carry the transition G755A (Arg252His) on the second allele. This novel mutation is the first Ballele to be associated with an adult phenotype.