No genetics course would be complete without

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Unformatted text preview: st have an affected father and either an affected or carrier mother. Example of an X-linked Recessive Trait • Hemophilia A: people bleed excessively, so that even small cuts and bruises can be life-threatening. • Mechanism: • Absence of a protein necessary for blood clotting, factor VIII. • Can be controlled by administering concentrated doses of factor VIII. • Inheritance: • The gene encoding factor VIII is located on the X chromosome. No genetics course would be complete without… Hemophiliacs tended to die young, without reproducing No hemophilia in current British royal family X-linked (Sex-linked) Dominant Traits • Affected males: all daughters affected. • Affected mothers have ½ affected sons and daughters and ½ normal sons and daughters. • Trait does not skip generations. Example of an X-Linked (Sex-linked) Dominant Trait • Hypophosphatemia: familial vitamin-D-resistant rickets. • Bone deformities, stiff spines and joints, bowed legs, and mild growth deficiencies. • Resistant to treatmen...
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