Am J Hum Genet 36:565-575, 1984 The Parental Origin of X Chromosomes in XX Males Determined Using Restriction Fragment Length

The inheritance of several X-linked restriction fragment length poly-morphisms (RFLPs) is examined in seven 46,XX males and their im-mediate relatives. The XX males are shown to have inherited a paternal and a maternal RFLP allele in each of the five (of seven) families in which these X-linked markers are informative. In the other two families, a maternal X-chromosomal contribution is demonstrated, but a paternal contribution cannot be determined. We conclude that most, if not all, XX males inherit one paternal and one maternal X chromosome. A segment of single-copy DNA specific to the short arm of the Y chromosome is found to be absent from the genomes of eight XX males. In one of these XX males, an Xp-Yp translocation had previously been inferred from chromosome-banding studies. Our findings argue against mosaicism involving a Y-containing cell line in the XX males examined here, but they do not exclude an X-Y (or Y-autosome) translocation during paternal meiosis. If such a translocation has occurred, the trans-location product received by the XX males does not include the Yp-specific sequence tested here