In Down syndrome, babies have 47 chromosomes rather than 46, and can have physical and developmental difficulties of differing degrees. Down syndrome testing has historically been invasive, including sampling of tissue and amniotic fluid, all of which have a slight risk for the unborn child, or have high false positive and false negative rates. Researchers in China believe they have found a protein biomarker in the mother's blood that could lead to a more accurate non-invasive test for Down syndrome.
The researchers took blood samples from 6 women carrying babies who were known to have Down syndrome, and 6 women whose babies were unaffected, and screened the blood for proteins. They found 29 proteins that were either at higher or lower levels in the women carrying Down syndrome babies. According to the researchers, this is the highest number of potential maternal biomarkers that have been found for Down syndrome.
Dr. Qiu wei Wang, one of the authors, said: "Among 29 proteins, two proteins, ceruloplasmin and complement factor B (CP and CFB), were the most notable. Both were significantly increased in DS maternal serum and their functional roles suggest a relationship with the development of DS."
Offering a prenatal test for Down syndrome, seen in 1 in 700 live births, provides parents with a choice over whether to proceed with the pregnancy or not. It also provides an early indication for those who do wish to keep the baby, giving them time to come to terms with the diagnosis and prepare themselves for a child that will need some level of extra support, both educationally and physically. The panel of proteins still needs clinical validation, and knowing more about these proteins could help researchers understand more about the syndrome, perhaps even leading to treatments for some of the symptoms.
Dr. Steven Goodman, editor-in-chief of Experimental Biology and Medicine, said in a feature article: "Prenatal screening for Down's syndrome has a rate of detection which is at best 75 to 85% with a 5% false positive rate and a lower rate of detection found in developing countries. The proteomic approach of [Dr. Shi-he] Shao and colleagues offers new biomarkers which could lead to higher rates of detection and lower false positive rates."