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Genetic and Rare Diseases Information Center (GARD)

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Wiskott Aldrich syndrome

Other Names for this Disease
  • Aldrich syndrome
  • Eczema thrombocytopenia immunodeficiency syndrome
  • IMD 2
  • Immunodeficiency 2
  • WAS
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How is Wiskott Aldrich syndrome inherited?

Wiskott Aldrich syndrome (WAS) is inherited in an X-linked recessive manner and therefore occurs almost exclusively in males.

X-linked recessive genetic disorders are conditions caused by an abnormal gene on the X chromosome.[1] The X chromosome is one of the two sex chromosomes (the other sex chromosome is the Y chromosome). Females have two X chromosomes in each cell and males have an X chromosome and a Y chromosome in each cell.

WAS is caused by mutations in the WAS gene on the X chromosome, thereby leading to a deficiency of the WASP protein, which is important in the structure and function of most blood cells.

Females have two X chromosomes, but one of the X chromosomes in each cell is "turned off" and all of the genes on that chromosome are inactivated. Females who have a disease gene present on one of their X chromosomes are carriers for that disorder. Carrier females usually do not display symptoms of the disorder because it is usually the X chromosome with the abnormal gene that is "turned off" and females have another X chromosome in each cell with a working copy of the WAS gene. 

A male has only one X chromosome, so if he inherits an X chromosome that contains a disease gene, he will develop the disease. Males with X-linked recessive disorders always pass the disease gene to all of their daughters, who will be carriers. A male cannot pass an X-linked gene to his sons because males always pass their Y chromosome instead of their X chromosome to male offspring. 

Female carriers of an X-linked recessive disorder have a 25% chance with each pregnancy to have a carrier daughter like themselves, a 25% chance to have a non-carrier daughter, a 25% chance to have a son affected with the disease, and a 25% chance to have an unaffected son.[1] This also means that each daughter has a 50% chance of being a carrier, and each son has a 50% chance of having the disease.
Last updated: 6/23/2011

  1. WAS Related Disorders. NORD. February 15, 2008; Accessed 6/15/2011.