CHARACTERIZATION OF THE MOLECULAR DEFECT IN A FELINE MODEL FOR TYPE-II G(M2)-GANGLIOSIDOSIS (SANDHOFF DISEASE)

The Korat cat provides an animal model for type II G(M2)-gangliosidosi s (Sandhoff disease) that may be suitable for tests of gene replacemen t therapy with the HEXB gene encoding the beta subunit of the beta-hex osaminidases. In the present report, we examined the brain and liver p athology of a typical Sandhoff-affected cat. We characterized the feli ne HEXB complementary DNA (cDNA) and determined the molecular defect i n this feline model. cDNA libraries were produced from one normal and one affected animal, and cDNA clones homologous to human HEXB were seq uenced. In the affected cDNA clone, the deletion of a cytosine residue at position +39 of the putative coding region results in a frame shif t and a stop condon at base +198. This disease-related deletion was co nsistently detected by sequencing of cloned polymerase chain reaction amplified reverse transcribed messenger RNA from one more normal Korat and two additional affected animals. The defect was further demonstra ted using single-strand conformational polymorphism analysis of the po lymerase chain reaction products. In addition, alternative splicing of both normal and affected messenger RNAs was demonstated. These result s should facilitate the use of this animal model to assess gene therap y.