The condition in which there are more than two complete sets of chromosomes is called:

Gynecomastia is a symptom of

What is Down's syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down's syndrome increase if the age of the mother exceeds forty years?

$A$ human with $45$ chromosomes having only one $X$ chromosome $(XO)$ suffers from which of the following disorders?

$A$ disease caused by an autosomal primary non-disjunction is

An abnormal human male phenotype involving an extra $X$ chromosome $(XXY)$ is a case of