Sickle cell anaemia is due to

In man,the genetic disorder 'Aniridia' (congenital absence of the iris) occurs due to:

If a haemophilic man marries a woman carrier (heterozygous) for haemophilia,what would be the possibility that their daughter would be haemophilic (in $\%$)?

Mr. Stevan is suffering from haemophilia and cystic fibrosis. His father is heterozygous for cystic fibrosis. The probability of Stevan's sperm having recessive $X$-linked as well as autosomal allele is

$A$ person whose father is colourblind marries a lady whose mother is the daughter of a colourblind man. Their children will be:

If a colourblind woman marries a normal man whose father was colourblind,what are the chances of their son being colourblind (in $\%$)?