Molecular basis of length polymorphism in the human zeta-globin gene complex.

Abstract
The length polymorphism between the human .xi.-globin gene and its pseudogene is caused by an allele-specific variation in the copy number of a tandemly repeating 36-base-pair sequence. This sequence is related to a tandemly repeated 14-base-pair sequence in the 5'' flanking region of the human insulin gene, which is known to cause length polymorphism and to a repetitive sequence in intervening sequence (IVS) 1 of the pseudo-.xi.-globin gene. The latter is also of variable length, probably because of differences in the copy number of the tandem repeat. The homology between the 3 length polymorphisms may be an indication of the presence of a more wide-spread group of related sequences in the human genome, which might be useful for generalized linkage studies.