Question

Hereditary rickets is a sex-linked dominant trait that results in low levels of vitamin D.

Which genotypes would result in someone having rickets? Check all that apply.
XHXH

XHY

XhY

XHXh

XhXh

Answer 1

XHXH, XHY, XHXh
Females who get at least one H (dominant) on an X (sex-linked) will display the trait/disorder but males must get the H on their only X

Answer 2

XHXH, XHY and XHXh

Step-by-step explanation:

For sex linked dominant trait, only one dominant allele on one of the X chromosome is needed for the trait to be phenotypically expressed. Both the male and the female need just just one dominant allele for the trait to be expressed.

This is as opposed to sex linked recessive trait in which the females which are XX need two of the alleles in order for the trait to be expressed while the males which are XY only need one.

Hence, for a sex linked dominant trait such as rickets, XHXH, XHY and XHXh will be affected for the trait.