A clinical and molecular study of 26 females with Xp deletions with special emphasis on inherited deletions.

We have undertaken a clinical study of 26 females with deletions of Xp including five mother-daughter pairs. Cytogenetic and molecular analyses have mapped the breakpoints of the deletions. We determined the parental origin of each abnormality and studied the X-inactivation patterns. We describe the clinical features and compare them with the amount of Xp material lost. We discuss the putative loci for features of Turner syndrome and describe how our series contributes further to their delineation. We conclude that (1) fertility can be retained even with the loss of two-thirds of Xp, thus, if there are genes on Xp for ovarian development, they must be at Xp11-Xp11.2; (2) in our sample of patients there is no evidence to support the existence of a single lymphogenic gene on Xp; (3) there is no evidence for a second stature locus in proximal Xp; (4) there is no evidence to support the existence of a single gene for naevi; (5) we suggest that the interval in Xp21.1-Xp11.4 between DXS997 and DXS1368 may contain a gene conferring a predisposition to hypothyroidism.