MOLECULAR ANALYSIS OF THE 18Q--SYNDROME - AND CORRELATION WITH PHENOTYPE

Seven individuals with deletions of the distal long arm of chromosome 18 were evaluated at the clinical, cytogenetic, and molecular levels. The patients had varying degrees of typical clinical findings associat ed with the 18q- syndrome. Cytogenetic analysis revealed deletions fro m 18q21.3 or 18q22.2 to qter. Somatic cell hybrids derived from the pa tients were molecularly characterized using ordered groups of probes i solated from a chromosome 18-specific library. In general, the size of the deletion could be correlated with the severity of the phenotype. Based on the clinical pictures of these seven patients, a preliminary phenotypic map for the clinical features associated with deletions of the distal portion of the long arm has been generated. Furthermore, ge nes previously localized to 18q21 were mapped relative to the chromoso me breakpoints present in these patients.