Class 12 NEET Biology Principles of Inheritance and Variation Questions Part 1

Down's syndrome (Mongolian Idiocy, Mongolism) is caused by the presence of an extra chromosome number 21. Sickle cell anaemia is not a sex linked ( i.e., X linked) disease but an autosomally inherited recessive trait.
Haemophilia is X-linked but not holandric\/Y-linked. Parkinson's disease is a degenerative disease. It is not at all hereditary.