Two cases, classified as cryoglobulinaemic vasculitis based on a history of recurrent episodes of purpura, nephritis and in one case a peripheral neuropathy, the presence of cryoglobulins, low C4, and disease evolution on follow-up, additionally fulfilled the histological item of the EULAR/PRINTO/PRES criteria – i.e. the demonstration of predominant IgA immunoglobulin deposits on the skin biopsy. The gene discussed is CD79A; the disease is nephritis.