Any non-syndromic X-linked intellectual disability in which the cause of the disease is a mutation in the USP9X gene. The disease is MONDO_0010487 (intellectual disability, X-linked 99). Also known as: USP9X non-syndromic X-linked intellectual disability, intellectual developmental disorder, X-linked 99, X-linked recessive, intellectual disability, X-linked type 99, mental retardation, X-linked type 99, non-syndromic X-linked intellectual disability caused by mutation in USP9X.