New somatic cell hybrids for physical mapping in distal Xq and the fragile X region

Somatic cell hybrids were constructed from 3 patients carrying X chromosome abnormalities with breakpoints in distal Xq: 1) 94-3, from a patient with 46,XX,t(X;15)(q25 or q26;q25), 2) 8121-A1, from a patient with 46,X,del(X)(q26), and 3) 2384-A2, from a patient with 46,X,del(X)(q27). The breakpoint of patient 94 is proximal to HPRT in q26, a significant distance from the fragile X locus. The breakpoint of patient 8121 is distal to F9, but proximal to DXS98, and is thus proximal to the fragile site region. The breakpoint of 2384 is distal to DXS98 but proximal to DXS52, placing it within the region of the fragile site. Use of these physical mapping reference points will aid in the rapid localization of new DNA markers to distal Xq and the fragile X region.