Haemophilia is a sex linked recessive disorder of humans. The pedigree chart given below shows the inheritance of Haemophilia in one family. Study the pattern of inheritance and answer the questions given.

(a) Give all the possible genotypes of the members 4, 5 and 6 in the pedigree chart.
(b) A blood test shows that the individual 14 is a carrier of gaemophilia. The member numbered 15 has recently married the member numbered 14. What is the probability that their first child will be a haemophilic male ? Show with the help of Punnett square.

Explanation

(a) Haemophilia is a sex linked recessive disorder of humans, where even a small cut or wound can be fatal as the blood of the patient does not clot.
`**" "`Possible genotype of member 4 in the pedigree chart is either XX (normal female) or `X X^(h)` (carrier female).
`**" "`Genotype of member `5=X^(h) Y` (Haemophilia man)
`**" "`Genotype of member `6=XY` (normal male)
`{:(14,,15),(X^(h)X,X,XY),(("Carrier Female"),,("Normal Male")):}`

`X^(h)X=` Carrier female
X^(h)Y=` Haemophilia Male
`X X=` Normal female
`XY =` Normal male
The probability of first child to be haemophilia male is `25%`.