Fetal nuchal translucency and prenatal diagnosis of beta-thalassaemia

In Sardinia, fetal karyotyping for couples at risk for beta-thalassaemia is offered only to women greater than or equal to 35 years and for specific r isk of chromosomopathies. This policy is not easily accepted by the couples who insistently request additional karyotyping. In order to select those a t highest risk of chromosomal abnormalities among young women, fetal nuchal translucency (NT) thickness measurement was performed in 510 fetuses to as sess the chromosomal risk before chorionic villus sampling. A risk greater than or equal to 1/100 was judged positive and worthy of additional karyoty ping. 126 cases interrupted the pregnancy after a result of homozygous P-th alassaemia, hence 384 pregnancies were included in the study. 22 (5.7 per c ent) fetuses were found NT positive. A total of three chromosomal abnormali ties were detected. The NT test was positive in all three cases of chromoso mopathies detected (100 per cent) and in 19 of 381 (4.98 per cent) normal k aryotype fetuses. No features of major chromosomal abnormalities were repor ted among the newborns whose NT had resulted normal. These preliminary resu lts have confirmed the efficacy of NT testing to assess the risk of trisomy 21 and other chromosomopathies and enhanced its utility in pregnancies alr eady suited to sampling in the first-trimester for Mendelian disorders. Cop yright (C) 1999 John Wiley & Sons, Ltd.