EP06.45: Prenatal diagnosis of Temple syndrome in the second trimester

Temple syndrome is an highly rare genetic condition characterised by distinct facial features, developmental delay, growth restriction, precocious puberty, and abnormalities of the hands and feet. Recent discoveries attribute this condition to maternal uniparental disomy of chromosome 14 (UPD(14)mat) in the 14q32.2 region. Despite its recognition, the syndrome's incidence remains uncertain with fewer than 100 cases described postnatally. This report introduces the first prenatal diagnosis of Temple syndrome in a 41-year-old woman during her second pregnancy. Despite a low-risk first trimester screening, she opted for the NIPT test which indicated a low risk for common trisomies, however with the possible risk of trisomy 14. Amniocentesis was performed and CGH array from uncultured amniocytes showed a low-level mosaic of trisomy 14. Subsequent conventional karyotype from cultured amniocytes revealed normal karyotype 46, XX, but FISH examination found a 3.6% mosaic of trisomy 14. The ultrasound examination at 19 and 21 weeks showed early growth restriction, atypical profile with micrognathia, single umbilical artery, valgus deformity of the right foot and fibroelastosis of the left ventricle. The targeted QF PCR examination for uniparental disomy was added and UPD(14)mat associated with Temple syndrome was revealed. The pregnancy was terminated and subsequent autopsy confirmed all ultrasound findings and in addition, described low-set ears with accessory tragus. The discordance in results from NIPT and amniocentesis can be explained by the presence of placental mosaicism for trisomy 14 with fetal UPD(14)mat. To conclude, we presented a second trimester prenatal detection of a rare syndrome with subtle ultrasound findings, dominated by early growth restriction. This case underscores the complexity of prenatal genetic diagnosis, particularly in the context of placental mosaicism, and highlights the importance of comprehensive testing in detecting rare genetic syndromes.