X-linked intellectual disability, Siderius type

X-linked intellectual disability, Siderius type is a condition characterized by mild to moderate intellectual disability that affects only males. Affected boys often have delayed development of motor skills such as walking, and their speech may be delayed.

Individuals with X-linked intellectual disability, Siderius type frequently also have an opening in the lip (cleft lip) with an opening in the roof of the mouth (cleft palate). A cleft can occur on one or both sides of the upper lip.

Some boys and men with this condition have distinctive facial features, including a long face, a sloping forehead, a broad nasal bridge, a prominent bone in the lower forehead (supraorbital ridge), and outside corners of the eyes that point upward (upslanting palpebral fissures). Affected individuals may also have low-set ears and large hands.

Other names

MRXSSD; Siderius X-linked mental retardation syndrome; Siderius-Hamel syndrome; Syndromic X-linked mental retardation, Siderius type; X-linked mental retardation Hamel type; X-linked mental retardation Siderius type

Inheritance pattern

X-linked recessive

Related genes

PHF8

Source: MedlinePlus Genetics, U.S. National Library of Medicine.