Prenatal Diagnosis of Williams Beuren Syndrome

In this chapter, we explain a rare case of prenatal Williams-Beuren syndrome diagnosis (WBS). While prenatal diagnosis of WBS is extremely rare, in this case, WBS was discovered in the early stages of pregnancy. The detection of fetal hands hypotonia and generalized fetal hypotonia at 17 weeks of gestation was critical. WBS was diagnosed using molecular karyotyping, particularly array comparative genomic hybridization (arrayCGH) of the fetal DNA. The genetic material was obtained by extracting it from fetal cells, which are abundant in amniotic fluid obtained through amniocentesis. Clinical hypotonia is a clinical feature that is generally associated with WBS; however, fetal hypotonia has not been characterized as a diagnostic criterion for the prenatal diagnosis of WBS. Keywords: prenatal genetic testing, fetal medicine specialist, first trimester scan, fetal hypotonia, williams-beuren syndrome