Physical localization of chromosome 20 markers using somatic cell hybrid cell lines and fluorescence in situ hybridization.

A panel of somatic cell hybrid cell lines containing different parts of human chromosome 20 and fluorescence in situ hybridization have been used to physically localize markers to human chromosome 20. Through these complementary approaches and genetic linkage analysis, D20S16, which is closely linked to the maturity onset diabetes of the young (MODY) locus, was mapped to band 20q12 --> q13.1. The gene for growth hormone-releasing factor (GHRF) was physically mapped and reassigned to 20q11, suggesting that GHRF plays no direct role in MODY. In addition, the genes for the chromosome 20-linked glycogen phosphorylase (GYPB) and the bone morphogenetic protein (BMP2A) have been assigned to chromosome 20p, and the interleukin-6-dependent DNA-binding protein (TCF5) has been assigned to 20q12 --> q13 by hybridization to genomic DNA from the panel of somatic cell hybrid cell lines. These approaches are useful for rapid localization of candidate genes for MODY and other DNA markers mapped to chromosome 20.