LAUSR

This case presents a rare condition of placental diploid-triploid mosaicism in a pregnancy that was initially found to have a normal diploid complement for chromosomes 13, 18 and 21 on a culture of cells from chorionic villus sampling (CVS). Partial molar pregnancy is a trophoblastic disease caused by a genetic disorder, such as an additional haploid set of chromosomes, which results in a total of 69 chromosomes. When molar changes exist alongside the living foetus, the patient can be offered close observation; however, the majority of these pregnancies represent dizygotic twin pregnancies as a result of either complete (CHM) or partial (PHM) mole associated with a normal co-twin. There are cases described in the literature of live births with molar pregnancies, although these are rare and the mother is at an increased risk of pregnancy complications such as pre-eclampsia. This case represents a mosaic karyotype of two cell lines: a normal female cell line and a triploid cell line with an XXY sex chromosome complement identified in the placental sample and at a low level in the amniotic fluid sample. This has been very rarely reported in the literature (Sarno et al. 1993).