GENETICS PLEASE ANSWERQUESTIONFULLY SolutionD Two sets of tw

Solution

D. Two sets of twins in pedigree are Fraternal twins genetically. In II1 and II2, One boy is affected with disease and other boy is unaffected. The affected boy may have possibly X-Linked Recessive Inheritance where he would have got one carrier X chromosome from carrier mother and other Y chromosome from father. And Second boy from same pair would have got normal X chromosome from mother and a normal Y from father.

Another pair of twins has both kids affected with disease: One Boy affected and other girl also affected. It can be Autosomal dominant inheritance because just one abnormal X chromosome is passed from carrier mother to both the kids. But another X has come from normal father resulting into a girl, and a Y from normal father resulting into a boy. But because only on ecopy of affected chromosome is sufficient to cause disease, both kids of second pair have disease.

E. Mode of inheritance- Autosomal dominant

Probability= 3/4

because xY cross Xx---> 1xx, 1Xx,1Yx, 1YX

x brings affected phenotype.