A very severe phenotype of RSTS1, also known as the chromosome 16p 13.3 contiguous deletion syndrome, caused by large deletions including the CREBBP gene and the 3’ adjacent genes, viz., DNASE1 and TRAP1 [28], always exhibits severe mental retardation, life-threatening infections and systemic complications, and other classic features [30]. The gene discussed is CREBBP; the disease is infection.