Prenatal diagnosis of low-level mosaicism for trisomy 21 with rare karyotype detected by noninvasive prenatal testing

摘要

Trisomy 21 (Tri21), which causes the Down syndrome (DS), is the most common chromosome abnormality [1]. Patients with DS are always accompanied by intellectual disability, congenital heart disease and so on. Therefore, only 20% of Tri21 may progress to term delivery, but it is necessary to prevent the birth of neonatus with Tri21 [1], [2]. Noninvasive prenatal testing (NIPT), which is the newest detection method, provides a more precise and fast screening method for the early detection of Tri21, and the detection rate is more than 99% [3]. Nevertheless, the effect of the application of NIPT in the detection of aneuploidy chromosome mosaicism is still uncertain, and it poses a challenge for clinicians to deal with the genetic consultancy of low-level mosaicism after being detected by hypersensitized NIPT. In this article, we present a prenatal diagnosis of low-level mosaicism for trisomy 21 with rare karyotype detected by NIPT.