down syndrome: current status, challenges and future perspectives

down syndrome (ds) is a birth defect with huge medical and social costs, caused by trisomy of whole or part of chromosome 21. it is the most prevalent genetic disease worldwide and the common genetic cause of intellectual disabilities appearing in about 1 in 400-1500 newborns. although the syndrome had been described thousands of years before, it was named after john langdon down who described its clinical description in 1866. scientists have identified candidate genes that are involved in the formation of specific ds features. these advances in turn may help to develop targeted therapy for persons with trisomy 21. screening for ds is an important part of routine prenatal care. until recently, noninvasive screening for aneuploidy depends on the measurement of maternal serum analytes and ultrasonography. more recent progress has resulted in the development of noninvasive prenatal screening (nips) test using cell-free fetal dna sequences isolated from a maternal blood sample. a review on those achievements is discussed.