Prenatal Diagnosis of Triploidy in Fetus with Unexpected Chromosomal Translocation of Maternal Origin

Abstract

Triploidy is a lethal chromosomal abnormality. Fetuses with triploid condition have a tendency to die in early conception and very few survive to term. In this study, we report the prenatal diagnosis of fetal triploidy with unexpected chromosomal translocation. A 27 years old women was referred to our clinical cytogenetic department due to history of previous conceptus with intrauterine growth retardation at 21-22 weeks of gestation and in present pregnancy, the quadruple marker screen test had suggested a high risk for Trisomy 18 with the risk >1:50. The study was performed on the amniotic fluid and peripheral blood samples received at the clinical cytogenetics department. The interphase FISH and conventional karyotype methods were followed. The prenatal diagnosis using an amniotic fluid sample found a triploid fetus with unexpected balanced chromosomal translocation: 69, XXX,t(2;9)(q11.2;p22)x2. Later the origin of translocation was confirmed by parental chromosomal study. Cytogenetic analysis showed the presence of translocation involving chromosome 2 and 9 in the mother which confirms the maternal origin of translocation in fetal triploidy. Prenatal diagnosis of fetal triploidy with balanced translocation of maternal origin is a rare finding. In present study, the triploidy arises from the failure to expel the second polar body. It is important to perform prenatal fetal imaging with ultrasound at 18-22 weeks to identify any fetal anomalies or intrauterine growth retardation which is associated with triploidy.

Keywords: Prenatal diagnosis; amniocentesis; aneuploidy detection; balanced translocation; fetal abnormality; genetic counseling.

Fig.1

A GTG banded karyotype of the fetus 69,XXX,t (2;9)(q11.2;p22)x2