Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.

Exaggerated anterior convexity of the thoracic vertebral column.

A defect of the chest wall characterized by a depression of the sternum, giving the chest ("pectus") a caved-in ("excavatum") appearance.

Congenital fibrosis of the extraocular muscles (CFEOM) is a disorder of the nervous system that affects use of the muscles that surround the eyes (extraocular muscles). These muscles control eye movement and the direction of the eyes (for example, looking straight ahead). CFEOM impairs control of these muscles. As a result, affected individuals are unable to move their eyes normally. Most people with this condition have difficulty looking upward, and their side-to-side eye movement may also be limited. The eyes may look in different directions (strabismus). Instead of moving their eyes, affected individuals may need to turn their head to track moving objects. Additionally, most people with CFEOM have droopy eyelids (ptosis), which further limits their vision.\n\nResearchers have identified several forms of CFEOM, designated CFEOM1, CFEOM2, CFEOM3, and Tukel syndrome (sometimes called CFEOM4). The specific problems with eye movement vary among the types, and some types are associated with additional signs and symptoms. People with CFEOM1 and CFEOM2 have only the eye problems described above. In CFEOM1, the eyes typically point downward, whereas in CFEOM2, the eyes usually turn outward.\n\nCFEOM3 can include additional neurological problems, such as intellectual disability; difficulty with social skills; a smaller-than-normal head size (microcephaly); muscle weakness in the face; nonfunctioning vocal cords; and a set of symptoms called Kallmann syndrome, which features delayed or absent puberty and an impaired sense of smell. Some affected individuals develop pain, weakness, or a decreased ability to feel sensations in the limbs (peripheral neuropathy), which can begin in childhood or adulthood.\n\nBrain abnormalities can also occur in people with CFEOM3. Some have abnormal development of the white matter, which is brain tissue containing nerve cell fibers (axons) that transmit nerve impulses. A particular form of CFEOM3, known as CFEOM3 with polymicrogyria, is characterized by abnormal development of the brain, in which the folds and ridges on the surface of the brain are smaller and more numerous than usual.\n\nTukel syndrome is characterized by missing fingers (oligodactyly) and other hand abnormalities in addition to problems with eye movement.

Flatness of the supraorbital portion of the frontal bones.

Height of the vermilion of the upper lip in the midline more than 2 SD below the mean. Alternatively, an apparently reduced height of the vermilion of the upper lip in the frontal view (subjective).

Increased height of the central portion of the eyebrow, forming a crescent, semicircular, or inverted U shape.

Fibrosis of only some of the external ocular muscles such that the eyes of affected individuals are partially or completely fixed in a strabismic position.