Fine Assignment of 3-Hexosaminidase A ar-Subunit on 15823-q24 by High Resolution In Situ Hybridization

TAKEDA, K., NAKAI, H., HAGIWARA, H., TADA, K., SHOWS, T.S., BYERS, MG. and MYEROWITZ, R. Fine Assignment of R-Hexosaminidase A a-Subunit on 15g23-q24 by High Resolution In Situ Hybridization. Tohoku J. Exp. Med., 1990, 160 (3), 203-211 Tay-Sacks disease results from mutation in the gene encoding /3-hexosaminidase A a-Subunit. Although some reports have suggested the locus on 15q, we tried to determine the finer gene locus using high resolution in situ hybridization. cDNA probe, p RH a-5, containing the full-length sequence for the enzyme subunit, was 3H-labeled within 1-4>< 10' cpm/,ug of cDNA by nicktranslation. After molecular hybridization and autoradiography, prometaphases were G-banded by Hoechst 33258, UV-exposure and Giemsa. A total of 227 silver grains on chromosomes within 115 prometaphase spreads were analyzed. The region 15g23-q24 had 27 grains, corresponding to 11.9% of the total grains and to 77.1% of the grains on chromosome 15. 20.9% of prometaphases were observed with a grain at 15823-q24. According to several previous reports, the shortest region of overlap (SRO) of the locus has been 15822-g25.1. Here we have assigned the gene locus to the narrower region 15g23-q24 by high-resolution in situ hybridization, which is one of the most powerful strategy for the completion of human gene map. Tay-Sacks disease ; f3-hexosaminidase A a-subunit ; human gene mapping ; high resolution in situ hybridization