Fetal DNA that is circulating in the blood of pregnant women is frequently extracted noninvasively and screened for common chromosome aneuploidies that cause disease such as trisomy of chromosome 21, which may result in Down syndrome. There are numerous other syndromes that are caused by single gene mutations that cannot be assessed like this. Zhang et al. developed a next-generation DNA sequencing approach for circulating fetal DNA that can detect alterations in 30 genes that cause monogenic disorders. Tests were performed on 422 pregnant women, and follow-up studies confirmed 20 positive results and 127 negative results, with no reported false-negative or false-positive results, suggesting that the method is highly specific and accurate.
