What is Down’s syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years?

Down’s syndrome

• Caused due to presence of an additional copy of chromosome number 21 9trisomy of 21)

• Affected individual is short statured with small round head, furrowed tongue and partially opened mouth. Palm is broad with characteristic palm crease. Physical, psychomotor and mental development is retarded.

• Karyotype with 23 pairs of autosomes and 1 pair of sex chromosomes. (total of 24 pairs i.e. 47 chromosomes).

The chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years because ova are present in females since their birth and therefore older cells are more prone to chromosomal non disjunction because of various physico-chemical exposure during the mother’s life time.