Neonatal detection of Turner syndrome by real-time PCR gene quantification of the ARSE and MAGEH1 genes

Abstract

Turner syndrome (TS) is characterized by the presence of one full X chromosome and total or partial deletion of the second sex chromosome. Diagnosis of TS is often delayed, resulting in inappropriate treatment. Early diagnosis of TS using a neonatal screening test may improve preventive measures and treatment, thus improving patient quality of life. The goal of this study was to standardize a neonatal TS screening algorithm. Two study genes (ARSE and MAGEH1) and 1 normalizing gene (HBB) were used to detect the second X chromosome. We screened 996 newborns whose peripheral blood was collected and stored in filter paper. In addition, samples from 20 patients with confirmed diagnosis of TS were included in the study. Relative amounts of ARSE/HBB were determined using real-time polymerase chain reaction. The cutoff at the 5th percentile was arbitrarily set to indicate repetition of the test. The test was repeated in 51/1016 patients with ARSE/HBB < 0.81. For 10 samples with values persistently <0.81, we quantified the MAGEH1/HBB ratio. Values below the 95th percentile in TS patients (MAGEH1/HBB < 1.24) were considered to be inadequate. Only 6/996 NB showed inadequate values for the 2 studied genes, which were recalled for clinical evaluation and karyotype testing. Analysis of 20 patients diagnosed with TS allowed for identification of false-negatives and true-positives, establishing 95% sensitivity when the indicated cutoff values were used. In conclusion, our algorithm reached 95% detection sensitivity with an acceptable recall rate (0.6%), allowing for the detection of suspected TS cases in the neonatal period.