Ring chromosome 13 in a polymalformed anencephalic.

In the 33rd week of pregnancy an amniocentesis was performed because of low estriol. X-ray indicated the presence of anencephaly and a premature delivery was induced. Necropsy, in addition to anencephaly, showed a wide variety of malformations. The fetal karyotype determined from cultured amniotic fluid cells revealed a ring chromosome 13.