Before its identification as the cause of XLP-1, we had independently cloned a full-length SAP/SH2D1A cDNA (GenBank: AB586694.1) from mRNAs isolated from peripheral leukocytes of a patient with IgA nephropathy, which is also known as EBV-related disease. The gene discussed is SH2D1A; the disease is IgA glomerulonephritis.