XSIQ
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Biology - Inheritance of X-linked dominant characteristics

Inheritance of X-linked dominant characteristics

X-linked indicates that the allele [1] is on the X-chromosome and
therefore linked to the sex of the individual. For example, XRXR, XRXr or
XRY or XrY. Which individuals would express (show) the characteristic?

* All daughters of affected fathers will show the characteristic (if the
father is affected he has one X chromosome with the defective allele; this
would be passed on to the daughter)

* An affected son must have an affected mother (a son has one X
chromosome from his mother; if he has the characteristic then the mother
must have been affected)

* More females than males are likely to show the characteristic.

Examples of genetic disorders following the X-linked dominant pattern of
inheritance include:

* weakness and wasting of the muscles of the legs and hands

* vitamin-D resistance for rickets

* There are only a few X-linked dominant disorders. Can you suggest why?

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Links:
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[1] http://alison.com/#