2086260 The Prenatal Diagnosis of Microdeletion/Microduplication Syndromes in Increased Nuchal Translucency with Normal Karyotype: Unselected Korean Populations

Abstract

Though the presence of aneuploidy is ruled out, nuchal thickening is clinically associated with many problems. Some reports have examined the value of microdeletion testing in increased NT fetuses, normal karyotype and no structural anomalies, but the results have showed limited value. The purpose of this study was to assess the value of testing for microdeletion/micoduplication syndromes with NT greater or equal to 95th percentile according to crown-rump length and normal karyotype. During April 2010 to December 2013, a total of 3051 samples had a routine karyotyping and MLPA analyses performed for several indications. Among them a total of 974 pregnancies were collected the inclusion criteria of increased NT. All samples were processes for G-banding karyotyping in additional to rapid aneuploidy testing and Multiplex Ligation dependent-Probe Amplification (MLPA). The MLPA analysis for detection of microdeletion or microduplication syndrome were performed using commercial MLPA kits (SALSA P245,MRC- Holland, Netherland). Application of the screening detected 26 cases of microdeletion/microduplication syndromes in 3051 samples (0.85% incidence). Among the 974 in increased NT samples with a normal karyotype, we identified 3 cases of microdeletion syndromes; 1 cases of DiGeorge syndrome (22q11 deletion), 1 cases of Wolf- Hirschhorn syndrome (4p 16.3 deletion), 1 Sotos syndrome and 9 cases of microduplication syndromes(3q,7q,10p,15q,17q,22q). The diagnostic yield was 1.23%(12/974) in the thick NT, 0.73%(4/545) in advanced maternal age and 0.35%(3/843) in the high risk result following maternal serum biomarker screening. This is the largest single reported study of microdeletion/microduplication syndromes in increased NT fetuses with normal karyotype. The prevalence of microdeletion/microduplication syndromes with increased NT is obviously higher than that expected in the general population. For this reason, the additional MLPA analyses for selected microdeletion/microduplication syndrome are valuable and useful in counselling parents of pregnancies with increased NT.