High Quality Content by WIKIPEDIA articles! Lujan–Fryns syndrome (LFS), also referred to as X-linked mental retardation with Marfanoid habitus and Lujan syndrome, is an X-linked genetic disorder that causes mild to moderate mental retardation and features described as Marfanoid habitus, referring to a group of physical characteristics similar to those found in Marfan syndrome. These features include a tall, thin stature and long, slender limbs. LFS is also associated with psychopathology and behavioral abnormalities, and it exhibits a number of malformations affecting the brain and heart. The disorder is inherited in an X-linked dominant manner, and is attributed to a missense mutation in the MED12 gene. There is currently no treatment or therapy for the underlying MED12 malfunction, and the exact etiology of the disorder remains unclear.