The infant is suffering from Down’s syndrome that is caused by the presence of an extra chromosome number 21. It is an autosomal aneuploidy. Both the chromosomes of the pair 21 pass into a single egg due to non-disjunction during oogenesis. Thus, the egg possesses 24 chromosomes instead of 23. The child will have short stature and a small rounded head. Palms of the child will be broad with characteristic palmer crease and his physical and mental development will be retarded.