Genes of colour blindness are carried in

Both a man and a woman are affected by Vitamin $D$-resistant rickets,which is an $X$-linked dominant trait. All the daughters of this couple are affected by rickets,but some of the sons are not. What are the genotypes of the parents?

If a normal woman marries a colourblind man,what will be the phenotype of their children?

In the $\beta$-globin chain of haemoglobin of an individual,if the sixth amino acid,Glutamic acid (Glu),is replaced by Valine (Val),then the individual will be suffering from:

The $ . . . . . . $ is regarded as an inborn metabolic disorder.

Most studies on human genetics have been made through