WAS patients have increased susceptibility to infections, particularly of the ears and sinuses, and this immune deficiency has been linked to decreased antibody production and the inability of immune T cells to effectively combat infection. Genetics
WAS is associated with mutations in a gene on the short arm of the X chromosome (Xp11.23) that was originally termed the Wiskott-Aldrich syndrome protein gene and is officially known as WAS (Gene ID: 7454). X-linked thrombocytopenia (XLT) is also linked to pathogenic variants in the WAS gene, although some variants tend to be more strongly associated with XLT versus others that are more associated with WAS. The rare disorder X-linked neutropenia has also been linked to a specific subset of WAS mutations.The protein product of WAS is known as WASp. It contains 502 amino acids and is mainly expressed in hematopoietic cells (the cells in the bone marrow that develop into blood cells). The main function of WASp is to activate actin polymerization by serving as a nucleation-promoting factor (NPF) for the Arp2/3 complex, which generates branched actin filaments. Several proteins can serve as NPFs, and it has been observed that in WAS platelets the Arp2/3 complex functions normally, indicating that WASp is not required for its activation in platelets. In T-cells, WASp is important because it is known to be activated via T-cell receptor signaling pathways to induce cortical actin cytoskeleton rearrangements that are responsible for forming the immunological synapse.The severity of the symptoms produced by pathogenic variants in the WAS gene generally correlates with their effects on WASp.
Pityriasis commonly refers to flaking (or scaling) of the skin. The word comes from the Greek πίτυρον "bran". Classification
Types include: 

Pityriasis alba
Pityriasis lichenoides chronica
Pityriasis lichenoides et varioliformis acuta
Pityriasis rosea
Pityriasis circinata
Pityriasis rubra pilaris
Pityriasis versicolor
Dandruff, historically called Pityriasis capitis
Pityriasis amiantacea

See also
Desquamation
List of cutaneous conditions

References


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