Question

Which of the following human disorder does not follow Mendelian pattern of inheritance?

• A. Colorblindness
• B. Sickle cell anemia
• C. Down's syndrome
• D. Thalassemia

Answer 1

The correct option is C Down's syndrome

Mendelian disorder is controlled by the single locus of the inherited pattern. It means that even a mutation in a single gene can cause a disease e.g., thalassemia, sickle anemia, colourblindness, etc.

Down's syndrome is not inherited in Mendelian pattern, but occur as random events during the formation of reproductive cells (eggs and sperm). An error in cell division called nondisjunction results in reproductive cells with an abnormal number of chromosomes.