MAPPING OF THE X-BREAKPOINT INVOLVED IN A BALANCED X-12-TRANSLOCATIONIN A FEMALE WITH MILD MENTAL-RETARDATION

Balanced chromosomal abnormalities such as translocations and inversio ns have been identified in many genetic diseases. Cloning of the break points involved in these abnormalities has led to the identification o f the disease-related genes. Recent reports suggest the presence of a mental retardation locus at Xq11-12. We have identified a female patie nt with a balanced translocation t(X;12)(q11;q15) associated with mild mental retardation. We identified a yeast artificial chromosome spann ing the X-chromosome breakpoint by using fluorescent in situ hybridiza tion techniques. A cosmid library of this YAC has been constructed and the search for candidate genes is in progress.