We have used a panel of human x rodent somatic cell hybrids containing translocations involving chromosome 14 to regionally localize 17 genes and 5 random segments previously mapped to chromosome 14. Each hybrid cell line contains a specific fragment of chromosome 14, with breakpoints at 14q11.2, 14q21, 14q22, 14q24.3 or in two different regions of 14q32.1. The enzyme deficient in glycogen storage disease type VI, liver glycogen phosphorylase (PYGL), has been localized by in situ hybridization to 14q21-->q22, near the q21-->q22 band interface. Four additional genes, chromogranin A (CHGA), myosin (MYH7), tRNA proline 2 (TRP2) and c-FOS (FOS) and four random segments, D14S26, D14S12, D14S14 and D14S13 have been more precisely localized. This study also defines a hybrid cell panel with seven mapping intervals, that will be useful for further physical mapping of new loci.