Tay-Sachs and Sandhoff's disease: Intergenic complementation after somatic cell hybridization

Cultivated skin fibroblasts from patients with Tay-Sachs and Sandhoff's disease were fused and the isoenzymes of N-acetyl-β- -hexosaminidase were investigated after 2 and 7 days of subsequent cultivation. Enzyme analyses after heat inactivation showed a clear increase in the thermolabile component of hexosaminidase when compared with assays on fusion of each of the parental cell strains. Electrophoretic studies revealed that in cell homogenates prepared at various time intervals after cell fusion of Tay-Sachs with Sandhoff's fibroblasts, all three hexosaminidase isoenzymes were present, including hexosaminidase A which lacks in both parental cell strains. These results show that genetic complementation has occurred, which indicates that two different gene mutations are involved in these variants of GM2-gangliosidosis. The relevance of the data obtained for the elucidation of the molecular properties of the (iso)enzymes involved is discussed.