The lymphoid system of a patient with this syndrome appears anatomically intact from birth to five years of age. Eventually, however, there is a decrease in T cells in the paracortical areas of the lymph nodes and a polyclonal expansion of B cells. These patients have T cells that respond poorly to mitogens. The protein encoded by the WAS gene appears to be involved in signal transduction that leads to reorganization of the cytoskeleton when lymphocytes are stimulated. Defective collaboration between T cells and B cells occurs when the WAS gene is mutated.
Lymphocytes have a markedly abnormal appearance when visualized by scanning electron microscopy.
The platelets are abnormally small and few in number. Certain missense mutations in the WAS gene lead to a mild disease called X-linked thrombocytopenia. WAS patients may benefit considerably from splenectomy. It is characterized by cerebellar ataxia, starting at 18 months of age, followed by increasing tremor and deterioration of mental function. At five years of age, progressive telangiectasia is seen in the vessels of the bulbar conjunctiva and is later visible on the skin.