This news article cought my eye today: http://www.thehindu.com/todays-paper/tp-international/ill-not-abandon-gammy/article6281931.ece
The subject has already sparked a very valid ethical debate. In this context I wanted to get my basics right. So this is what down syndrome is:
1) congenital disorder (1 per 1000 babies born per year)
2) genetic disorder (child has a part or full extra copy of a third chromosome 21)
3) can be screened during pregnancy
4) Signs and symptoms: Patient will suffer from physical and intellectual disabilities. Patients have poor immune system. They are prone to several disorders viz. congenital heart disease, leukemia and thyroid disorders. The average IQ of a down syndrome adult is 50 – equivalent to a 8 or 9 year old normal child.
5) Genetics: Trisomy 21 (Trisomy-A condition in which an organism has one more than normal condition of two copies): Failure of 21st chromosome to separate during egg or sperm development. As a result the egg or sperm cell has 24 chromosomes instead of 23. When combined with normal cell of other parent, the embryo has 47 chromosomes-3 copies of chromosome 21.
I would like to keep this post as a stream, by adding basic information about various disorders that I come across.