RBMX and X-linked intellectual disability - psychosis - macroorchidism: Mental retardation, X-linked, syndromic 11 (MRXS11; also known as Shashi X-linked mental retardation syndrome; OMIM 300238) is associated with a hemizygous mutation in the gene encoding the RBP RBMX (also known as hnRNP G) [54].