X chromosome
This form of thrombocytopenia is inherited on X chromosome, thus individuals with this disorder are typically males. In regards to the sex chromosomes, males have one X chromosome and one Y chromosome while females have two X chromosomes. Because males only have one X chromosome, if they receive an X chromosome with a "WAS" gene mutation from their mother, then they will show phenotype of the condition. Females can be carriers for this disorder, which means that they have one normal X chromosome and one X chromosome with the "WAS" gene mutation. Females that are carriers do not show any signs or symptoms of X-linked thrombocytopenia.