Résumé:
Down's syndrome is the leading genetic cause of mental retardation and the most common chromosomal abnormality. In order to study the effect of maternal age on Down's syndrome, a study was conducted on 30 children with Down's syndrome.
Among the risk factors, maternal age would be the most favorable factor. One third of children with Down's syndrome are born to mothers over the age of thirty. The risk that the child is a carrier of Down's syndrome varies according to maternal age: under 30 years old 1/1500, between 30 and 34 years old 1/750, between 35 and 39 years old 1/280, between 40 and 44 years old 1 / 130. A woman over 45 has a 1/65 risk of having a child with Down's syndrome.
Advanced maternal age is responsible for an increase in meiotic non disjunction. This maternal non disjunction has been shown to be associated with recombination errors and possibly loss of chromosomal cohesion. It is the cause of an abnormality of chromosomal segregation during meiosis.
