Punnett Squares for X-Linked Dominant Conditions

Description: 
Below are sample Punnett squares for X-linked dominant conditions. The disease-causing mutation is denoted by the capital letter A. The normal gene is denoted by the lower case letter a .
Punnett Square

The Punnett square to the left is representative of possible reproductive outcomes should a female with an X-linked dominant mutation (clinically affected) have children with a male who is clinically unaffected.

This couple has a 25% chance with each pregnancy of having a daughter who inherits the mutation (clinically affected), a 25% chance of having an unaffected daughter, a 25% chance of having a son who inherits the mutation (clinically affected), and a 25% chance of having an unaffected son.



Punnett Square

The Punnett square to the left is representative of possible reproductive outcomes should a female without an X-linked mutation have children with a male who is clinically affected with an X-linked dominant condition.

This couple has a 50% chance with each pregnancy of having a daughter who inherits the mutation (clinically affected) and a 50% chance of having an unaffected son.



Punnett Square

The Punnett square to the left is representative of possible reproductive outcomes should a female who is heterozygous for an X-linked dominant condition (clinically affected) have children with a male who is also clinically affected with the same condition.

This couple has a 25% chance to have a daughter who inherits 2 copies of the mutation (clinically affected), a 25% chance to have a daughter who inherits 1 mutation (clinically affected), a 25% chance to have a son who inherits 1 mutation (clinically affected), and a 25% chance to have a son who inherits no mutation (unaffected).

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