Prenatal diagnosis and genetic counseling for three cases of fetuses with low-level mosaic Turner syndrome.

Turner syndrome, also referred to as congenital ovarian hypoplasia syndrome, is the most common sex chromosomal abnormality found in females. It results when one of the X chromosomes is missing, partially or completely. About half of the population with Turner syndrome have monosomy X (45,XO). The other 50% of the population has a mosaic chromosomal component (45,XO with mosaicism). The phenotype of patients with mosaic Turner syndrome may vary depending on the different mosaicism ratios. In this research, we provide a detailed description of three patients with low-level mosaic Turner syndrome. Combination of karyotype analysis, copy number variation sequencing, fluorescence in-situ hybridization, prenatal ultrasound, and genetic counseling is helpful for the prenatal diagnosis of mosaic Turner syndrome.