Prenatal Screening for Down Syndrome

Down syndrome ([DS] trisomy 21) is the most common cause of intellectual disability worldwide, affects approximately 1:500 pregnancies and is seen in 1:800 to 1:1,000 live births [1]. Down syndrome is the leading cause of prenatal chromosome abnormalities, accounting for 53% of all reported chromosome conditions. Genetic prenatal diagnosis (PD) for DS, since its introduction in the late 1960s, has evolved significantly. In order to limit the number of invasive procedures and improved detection rate. The majority of public current screening programs [2] for DS generally combine initial non-invasive risk screening strategies. Conventionally, prenatal testing (screening or invasive) for Down syndrome has been offered to women aged 35 or above because they are at a higher risk than younger women. However, the detection rate is as low as 30% while the rate of invasive testing can be as high as 30%. The American College of Obstetrics and Gynecology (ACOG) recommends that all pregnant women [3], regardless of their age, be offered screening for DS. Consequently, the routine offer of medical tests to pregnant women is usually a two-tier procedure, in many Western countries with a public health setting. This approach can detect 85% of Down syndrome at an invasive testing rate of 5%. The introduction Shell Fean Wong1* 1Department of Maternal Fetal Medicine, University of University of Hong Kong, Hong Kong *Corresponding author: Shell Fean Wong, Department of Maternal Fetal Medicine, University of Hong Kong, Pok Fu Lam Road, Hong Kong, Email: [email protected]