404: Tandem mass spectrometry for characterization of amniotic fluid

Abstract

To describe the Tandem Mass Spectrometry (TMS) pattern of amniotic fluid collected from normal pregnancies and those with non-immune hydrops (NIH) and severe symmetric growth restriction (ssIUGR), for the intent of detecting inborn errors of metabolism (IEM) Newborn screening utilizing TMS is available for over 50 inherited metabolic disorders. Presently, such screening is done in the immediate newborn period and has become common practice. Given that such diseases impinge upon fetal growth and development, we believe this test has the potential to be utilized in the fetal period for prenatal diagnosis of IEM. This marks the first attempt at describing the TMS pattern of AF from normal pregnancies, as well as those at risk for IEM, including NIH and ssIUGR fetuses. AF from study patients undergoing amniocenteses for other indications were sent for TMS analysis. These samples were then compared with corresponding maternal and neonatal blood samples that underwent the same TMS analysis. Results from this cohort were compared against samples obtained from a control group (normal appearing fetuses undergoing routine genetic amniocentesis) analyzed by TMS. 48 total patients were enrolled: 16 with NIH, 11 with ssIUGR, 21 patients without apparent risk factors. There were no cases of IEM. In all study patients, the overall TMS profile was characterized as “normal.” However, individual variations within the specific markers tested are noted as well as gestational age variations and will be fully described in the presentation. This study is the first to characterize normal AF TMS patterns derived from patients at low and higher risk for IEM. Since TMS has the potential to serve as a way to identify fetuses affected with IEM, it is important to characterize normal AF patterns first and this has been accomplished in this study. We seek to further refine the characteristic AF profiles of affected fetuses and are considering a larger patient population for study.