Partial trisomy 13 for the distal long arm and its prenatal diagnosis

: The results of prenatal diagnosis of fetal karyotype in a woman carrier of reciprocal t(13; 21) (q22; q22) translocation during her second pregnancy are presented. The first pregnancy ended in a term delivery of male twins with multiple malformations typical of the Patau syndrome. No cytogenetic investigation was carried out in this case. In the second pregnancy, unbalanced fetal 46,XX,21q+ karyotype was determined in amniotic cell cultures. The pregnancy was terminated after 19 weeks using intraamniotic PgF2 alpha. Phenotypical and pathoanatomical description of the aborted embryo presented corresponds to the clinical picture of the Patau syndrome. The 46,XX,21q+ karyotype was confirmed in fetal skin fibroblast cultures (skin biopsy specimens obtained during induced abortion), namely, partial trisomy for the distal part of the long arm (13q22) of chromosome 13 translocated to chromosome 21, as a result of inherited unbalanced variant of maternal translocation, was demonstrated. Comparative data on phenotype/karyotype correlation of individuals with partial trisomy 13 for distal part of the long aem of varying length are discussed.