Gene for Incontinentia Pigmenti Maps to Band Xp11 with an (X;10) (p11;q22) Translocation

Incontinentia pigmenti (IP) is a genetic disease that is usually lethal in males. We report finding an X;10 translocation in a girl with IP. Three other X/autosome translocations have been observed in females with IP: two involving chromosome 9 and one involving chromosome 17. The breakpoint in all four cases in the X chromosome was in band Xp11. The IP gene locus can therefore be confidently assigned to the X chromosome and, specifically, to band Xp11. The IP gene is most likely to subband Xp11.2. We propose that IP may prove to be a submicroscopic deletion.