Analysis of the spectrum of malformations in human fetuses of the second and third trimester of pregnancy with human triploidy.

Triploidy is constituted by an extra haploid set of chromosomes for a total of 69 chromosomes in humans. A "parent-of-origin" effect has been demonstrated by analysis of cytogenetic polymorphisms of triploidy pregnancies. Two distinct phenotypes of human triploid fetuses have been recognized according to the parental origin of the extra haploid set. The first one or triploidy of diandric type occurs when the extra haploid set of chromosomes arises from the father, the second one or triploidy of digynic type occurs when the extra haploid set of chromosomes arises from the mother. Diandric fetuses appear relatively well grown with a large placenta, while digynic fetuses show intrauterine growth retardation with a small placenta. Autopsy archive data files (1982-1998) of the Institute of Pathology, University of Heidelberg (Germany) were examined for fetuses with triploidy. We found 12 well-studied triploid fetuses (gestational age: 20 to 32 weeks). Eleven fetuses corresponded to the digynic type of triploidy and one fetus corresponded to the diandric type of triploidy. The spectrum of external malformations included a dysmorphic face (broad root of the nose, exophthalmos, low-set ears, micro-/retrognathia, microgenia, median cleft lip and/or palate, gnathoschisis, macroglossia), encephalocele, spina bifida, syndactyly, club or rocker-bottom feet, pes equino-valgus. More common internal malformations included ventricular septum defect of the heart, abnormal lobation of the lungs, and renal disease (agenesis, cysts).