AN ANALYSIS OF XQ DELETIONS

We characterized by fluorescence in situ hybridization and Southern bl otting 14 partial Xq monosomies, II due to terminal deletions and 3 se condary to X/autosome translocations. Three cases were mosaics with a XO cell line. In view of the possible role played by telomeres in chro mosome segregation, we hypothesize a relationship between the loss of telomeric sequences in terminal deletions and the presence of 45,X cel ls. A correlation between phenotype and extent of deletion revealed th at there is no correspondence between the size of the deletion and imp airment of gonadal function. Turner stigmata are absent in patients wi thout an XO cell line, when the breakpoint is distal to Xq24. A low bi rthweight is present whenever the breakpoint is at q22 or more proxima l.