We have completed a long-range restriction map of the terminal region of the short arm of human chromosome 16 (16p13.3) by physically linking a distal genetic locus (α-globin) with two recently isolated probes to telomere-associated repeats (TelBam3.4 and TelBam11). Comparison of 47 chromosomes has revealed major polymorphic length variation in this region: we have Identified three alleles in which the α-globin genes lie 170 kb, 350 kb, or 430 kb from the telomere. The two most common alleles contain different terminal segments, starting 145 kb distal to the α-globin genes. Beyond this boundary these alleles are non-homologous, yet each contains sequences related to other (different) chromosome termini. This chromosome size polymorphism has probably arisen by occasional exchanges between the subtelomeric regions of nonhomologous chromosomes; analogous length variation is likely to be present at other human telomeres.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)