Hypophosphatemia is manifested by an X-linked dominant allele.What proportion of the offsprings from a normal male and an affected heterozygous female will manifest the disease?

Question

Prepp Team · Accepted Answer

Understanding X-Linked Dominant Inheritance

Hypophosphatemia is caused by an X-linked dominant allele. This means the gene responsible is located on the X chromosome, and only one copy of the dominant allele is needed to express the trait.

Parental Genotypes

Normal Male: Genotype is X^hY. (X^h represents the normal allele, Y is the male chromosome).
Affected Heterozygous Female: Genotype is X^HX^h. (X^H represents the dominant disease allele, X^h represents the normal allele).

Punnett Square Analysis

We can predict the offspring genotypes using a Punnett square:

	X^h	Y
X^H	X^HX^h (Affected Female)	X^HY (Affected Male)
X^h	X^hX^h (Normal Female)	X^hY (Normal Male)

Offspring Phenotypes

Analyzing the Punnett square results:

Daughters (XX): Inherit one X from the father (X^h) and one from the mother (X^H or X^h).
- X^HX^h: Affected (1 out of 2 daughters)
- X^hX^h: Normal (1 out of 2 daughters)
Sons (XY): Inherit the Y from the father and one X from the mother (X^H or X^h).
- X^HY: Affected (1 out of 2 sons)
- X^hY: Normal (1 out of 2 sons)