Assignment of human genes coding for alpha-fucosidase (alphaFUC) and glucose dehydrogenase (GDH) to chromosome 1 has been confirmed and a location in the p21 leads to pter region demonstrated using man-mouse somatic cell hybrids. The regional location of alphaFUC and GDH was established in cell hybrids using human cells possessing 1/2 translocation chromosomes [46,XX,t(1;2)(p21;q37)]. Hybrids which retained the 2q+ chromosome carrying the 1p21 leads to 1pter region concordantly expressed alphaFUC, GDH, and the short-arm markers ENO1, AK2, and PGM1. Hybrids which retained the 1p21 leads to 1qter region only expressed human PEPC and FH. Data obtained from hybrids in which spontaneous breaks in chromosome 1 had occurred indicate that the gene order in 1p21 leads to 1pter is (ENO1,GDH)-alphaFUC-AK2-PGM1.