Abnormal behavior of the immune system and/or impairment of CBC are sometimes linked to in genes located to the X chromosome, like immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome, linked to the dysfunction of the transcription factor FOXP3, or Wiskott-Aldrich syndrome, another X-linked condition, caused by a mutation in the gene WAS, located on the short arm of X chromosome (Xp11.23); the latter is not so far from the one hypothesized for MCOPS1. This evidence concerns the gene WAS and Wiskott-Aldrich syndrome.