Prenatal diagnosis and molecular characterization of two constitutional rings derived from one chromosome 22.

摘要

In the medical literature, the first case of r(22) was reported by Weleber et al. [1968]. More than 60 cases of r(22) have been described since then. Most of these cases were diagnosed postnatally; the prenatal diagnosis of r(22) is very unusual. Moreover, there is no report of two constitutional r(22). A characteristic phenotype has not been fully delineated. However, the most consistent phenotypic findings are mental retardation, delayed motor functioning, and absence of major malformations [MacLean et al., 2000]. In general, microdeletions are beyond the resolution of conventional cytogenetic analysis, but some deletions of the terminal region of chromosome 22q are cytogenetically visible. We report on the first case of de novo two constitutional rings derived from one chromosome 22 causing partial monosomy 22 identified during prenatal diagnosis and characterized using cytogenetic and molecular genetic methods.