Some investigators reported that older fathers may also be at an increased risk of having a child with Down syndrome. It is well known that the extra chromosome in trisomy 21 could either originate in the mother or the father. Most often, however, the extra chromosome is coming from the mother. Contrary to popular belief, not every child with Down syndrome has all the characteristics - some may only have a few, and others may show most of the signs of Down syndrome. Many of these children will have to undergo cardiac surgery and often will need long term care by a pediatric cardiologist.
Intestinal abnormalities occur at a higher frequency.
Some children with Down syndrome, in particular those with severe heart disease often fail to thrive in infancy. On the other hand, obesity is often noted during adolescence and early adulthood. The latter condition occurs when the first two neck bones are not well aligned because of the presence of loose ligaments. Other important medical aspects include immunologic concerns, leukemia, Alzheimer disease, seizure disorders, sleep apnea and skin disorders. The estimated incidence of Down syndrome is between 1 in 1,000 to 1 in 1,100 live births.