The chromosomal deletion of Xq24q25 contains several dosage-sensitive genes, such as LAMP2, CUL4B, XIAP, SH2D1A and GRIA3. The deletion of XIAP and SH2D1A genes are the cause of X-linked lymphoproliferative disease [11]. The gene discussed is CUL4B; the disease is X-linked lymphoproliferative disease.