Sickle-cell anaemia happens due to ...$A$... mutation in which ...$B$... of haemoglobin is affected.

Fill the correct option for $A$ and $B$

Pick out the correct statements.

$I.$ Haemophilia is a sex-linked recessive disease

$II.$ Down's syndrome is due to aneuploidy

$III.$ Phenylketonuria is an autosomal dominant gene disorder

$IV.$ Phenylketonuria is an autosomal recessive gene disorder

$V.$ Sickle cell anaemia is an $X$-linked recessive gene disorder

If a man who is colour blind marries a women, who is pure normal for colour vision, the chances of their sons have colour blindness is

Sickle -cell anaemia has not been eliminated from the African population because it

Phenyketonuria is a genetic disorder of

$A$ - Sickle-cell anaemia is sex linked recessive trait

$R$ - This disease is controlled by more that two pair of alleles