Down syndrome genetic disease caused by abnormalities of chromosome autosome, some couples don't separate
.Children with Down syndrome is relatively small, flat head, flat nasal bridge and oblique eyes, small mouth, quite short, short hand often have congenital heart disease, the main problem is. Mental retardation
Chromosome 21 over 1 lines. making is amount The chromosome 47 line
cause is mother have children around the age of 30-45 years is risky