Clinical manifestations of familial 13;18 translocation

SUMMARY Female first cousins, aged 21 and 21 years, with many of the characteristic features of trisomy 18, were found to have identical unbalanced translocations, 46,XX,- 13, +der(13)t(13;18) (pl3;ql2)mat. Clinical features of another cousin, two uncles, and an aunt suggested that they, too, had a partial trisomy 18 phenotype. The long survival and normal menstrual and secondary sexual development in one case are remarkable. A heritable balanced translocation, 46,XX or XY, t(13;18) (pl3;ql2), was detected in the mothers of the cases, a sib, an aunt, and two uncles. Translocation carriers had abnormalities in gonadal structure or function, with aspermia in males and polycystic ovaries with infertility in several females, suggesting that some gene controlling reproductive develop-ment occurs on the long arm of chromosome 18, with normal function interrupted at the breakpoint. Balanced translocation carriers may also be at greater risk for both benign and malignant neoplasms, which included acute leukaemia in an uncle and adenocarcinoma of the stomach at an early age in the grandmother. Although aetiological laboratory studies identified no premalignant state, the clinical findings suggest a defect that may predispose to cytogenetic abnormalities and malignancy. Trisomy 18 is a well-characterised cytogenetic syndrome with an incidence in newborns of 0-01 %.