Trisomy 18q. A case report and review of karyotype-phenotype correlations.

A 2-month-old male infant with partial trisomy 18, 46,XY,der(4),t(q35;q21.1)mat, was presented. Except for atypical facies, he had many of the significant signs of full trisomy 18. Phenotype-karyotype correlations based on the data of our case and those from the literature were discussed. Major features of trisomy 18, such as congenital heart disease, early death, and external malformations, appear to be consistently related to the trisomic state of 18q21. Characteristic congenital heart diseases in trisomy 18 were polyvalvular disease in 100%, membranous ventricular septal defect, patent ductus arteriosus, and high take-off of the right coronary ostium. Pathology of the heart did not differ between full and partial 18-trisomy cases.