Question

In a dominant x-linked genetic disorder, what sex could be affected? Explain in details your answer citing all possibilities.

Answer 1

X linked genetic disorders are one which are associated with Sex chromosome X.

Female has karyotype of XX (So they have 2 X chromosome) while Males have karyotype of XY (so they have single X chromosome.

Depending upon the type of inheritence there are two types

1. X linked Recessive disorder

2. X linked dominant disorders

1. X-linked recessive inheritance i

This means that in a person with two X chromosomes (most females), both copies of a gene (i.e., one on each X chromosome) must have a mutation whereas in a person with one X chromosome (most males), only one copy of a gene must have a mutation.

A female with a mutation in one copy of a gene on the X chromosome is said to be a “carrier” for an X-linked condition.

A male with a mutation in a gene on the X chromosome is typically affected with the condition. Because females have two copies of the X chromosome and males have only one X chromosome,

X-linked recessive diseases are more common among males than females.

The most common X-linked recessive disorders are:

Hemophilia A

Hemophilia B

Red–green color blindness

Duchenne muscular dystrophy

X-linked Dominant Inheritance

For an X-linked dominant condition, only one copy of a gene on the X chromosome whether in a female with two X chromosomes or males with on X chromosome must have a mutation for an individual to be affected with the condition.

For this reason, X-linked disorders are often seen with similar frequency in males and females.

Examples are --

Vitamin D resistant rickets: X-linked hypophosphatemia.

Rett syndrome