X chromosome restriction fragment length polymorphisms in five racial groups: rare variant detected with the RC8 (DXS9) probe in the Marathi population, India.

Restriction fragment length polymorphisms were investigated in five racial groups using the X chromosome probes DXS9 and DXS7. The allele frequencies of these polymorphisms showed significant differences and both DNA fragments were found to be highly polymorphic in the populations of south and southeast Asia. In the Marathi population of India, a rare allele B3 (3 kilobases; kb) and an altered 7-kb fragment instead of the 6.6-kb constant band were found with DXS9. This is the first time that the rare B3 allele is found in a non-European population.