X-linked mental retardation with marfanoid habitus syndrome is a congenital disorder that is characterized by mental retardation in association with marfanoid features, distinct craniofacial appearance and behavioural problems. Marfanoid features describe the tall and stooped posture with long, hyper-extensible fingers and toes. The syndrome affects males more than females and it may occur more frequently among mentally retarded patients and psychiatric patients.
Recent studies have shown that Lujan-Fryns syndrome is caused by mutation in the MED12 gene.