Is a congenital disorder caused by the presence of extra chromosome in the cells of the body (trisomy 21)
Down syndrome is the one of the phenomena resulting from a defect in the chromosomes or genes
It causes varying degrees of mental retardation and physical imbalances
Down Syndrome infects one out of every 800 children, despite the fact that more than half of affected pregnancies Ptthelt chromosome 21 not continue (Ottaghdhan ).
With 75% of the embryos that have Down syndrome (chromosome 21 syndrome triple) ending abortion automatically without any medical intervention,
But he child is born to a friendly Down syndrome per 800 births of children alive. Also that 80% of children who have Down syndrome are born to mothers ages not exceeding 35 years, with the possibility of having a child with Down syndrome increases with increasing age of women and the reason for this is due to that most births (they were unharmed or is unharmed) born to mothers aged less than 35 years old!
Dr. English John Lzng Down in 1865 the first detailed description of the children with this syndrome, which later renamed named. The French Dr. Lejeune (Lejeune ) First discovered that Down syndrome caused by the presence of 3 copies of chromosome 21 instead of two copies.
