A century after Down syndrome was first described, scientists discovered that the root cause of this disorder is a condition called trisomy 21. What strides in research have been made since then?

Each human has 46 chromosomes, 22 pairs of autosomes and 1 pair of sex ... The recurrence risk with trisomy is 1% to 2% or the maternal age risk, whichever is greater. [2] There is a recurrence ...

There is also an apparent "bump" in trisomy among teenage girls. This slight increase has also been observed in several studies of Down syndrome, and might reflect a tendency to non-disjoin in the ...