Further evidence of no association between spinal muscular atrophy and increased nuchal translucency

Abstract

Introduction: Several authors have reported on pregnancy outcomes associated with enlarged nuchal translucency (NT) in cases of spinal muscular atrophy (SMA), and thus, thickened NT has been considered a possible early ultrasound scan sign of SMA. The purpose of our study was to evaluate the association between an increased NT and SMA in order to use an ultrasound scan of NT as a possible marker of this disorder.

Material and methods: This is a retrospective and observational study of women who had a fetus or delivered a baby with SMA following a pregnancy in which NT ultrasound has been performed. With the support of 'Famiglie SMA', we acquired copies of ultrasound NT measurements, molecular genetic tests confirming the SMA diagnosis in the fetus/baby, other prenatal ultrasound evaluations and informed consent.

Results: Twenty-nine Italian women met the inclusion criteria and sent us the requested reports. All had a normal NT measurement for the SMA-affected fetus, with a mean of 1.8 mm (range 0.9-2.4).

Discussion: This series does not confirm an association between increased NT and SMA. Fetal genetic testing for the survival motor neuron gene 1 on the basis of increased NT is not indicated in couples with no previous history of this genetic condition.