Genetic assessment following increased nuchal translucency and normal karyotype

The objective of this study was to assess the first formal approach for monitoring genetic/developmental syndromes associated with the presence of an increased nuchal translucency (NT) thickness (>3 mm) in the first trimester of pregnancy.

Multiple technologies-a DNA chip using the APEX technology, qPCR, microfluidic PCR, and sequencing-were applied to assay 310 mutations across five conditions-Noonan syndrome, congenital adrenal hyperplasia, spinal muscular atrophy (SMA), DiGeorge syndrome, and Smith-Lemli Opitz syndrome.

We report the results of assessing the first 120 patients in which 8 cases of Noonan syndrome were detected as well as an unusually high rate of heterozygosity for SMA.

While testing for Noonan syndrome in association with increased NT appears warranted, the reported association of the remaining four genetic syndromes is likely to be weak and possibly insignificant.