LAUSR

This was the first pregnancy of a non-consanguineous Thai couple. Antenatal screening revealed that the woman’s haemoglobin was 12.5 g/dl, MCV 82.2fL and mean cellular haemoglobin (MCH) 27.8 pg. Her husband’s haemoglobin was 15.4 g/dL, MCV 82.3fL and MCH 27.0 pg. Routine ultrasound at 21 weeks of gestation showed normal foetal anatomies. The amniotic fluid index was 20.9 cm. Because of the generous amniotic fluid volume at 21 weeks, she was scheduled to have a repeat ultrasound in two weeks. On ultrasound at 23 weeks, the amniotic fluid index was 27.5 cm and the foetus had cardiomegaly (cardiothoracic ratio 0.56). The foetal middle cerebral artery peak systolic velocity (MCA PSV) was 47 cm/s (corresponding to 1.6 multiples of median). Cordocentesis revealed that the foetal haemoglobin was 3.3 g/dL, MCV 122fL. Maternal Kleihauer test, autoimmune markers and viral studies, including that for Parvovirus B19, were all negative. Intrauterine foetal death was noted at 24 weeks. The post-mortem examination was unremarkable. Haemoglobin analysis (brilliant cresyl blue stain for HbH inclusion bodies and high performance liquid chromatography) was suggestive of HbE trait with co-existing alpha thalassaemia. Genotyping unveiled that she was in fact double heterozygous for Haemoglobin E and Haemoglobin Constant Spring (HbCS). Despite normal haemoglobin analysis, her husband was confirmed to be heterozygous for HbCS by genotyping. The foetus was homozygous for HbCS.