We have detected and characterized a highly polymorphic marker that ma
ps to the centromere of human chromosome 5. The localization was estab
lished by both linkage analysis within the CEPH reference families and
fluorescence in situ hybridization. The marker consists of a sequence
of five nucleotides, (CCTTT)(n). Nineteen alleles have been detected
in 46 unrelated individuals from 12 CEPH families, with a calculated h
eterozygosity of 0.91. This is the first truly centromeric, highly pol
ymorphic genetic marker described so far.