Underdevelopment of the fibula.

Length of the thumb is greater than normal.

Flattening of the superior part of the acetabulum, which is a cup-shaped cavity at the base of the hipbone into which the ball-shaped head of the femur fits. The acetabular roof thereby appears horizontal rather than arched, as it normally does.

Ossification of carpal bones occurs later than age-adjusted norms.

Increased side-to-side width of a metatarsal bone.

Short (hypoplastic) middle phalanx of finger, affecting one or more fingers.

An abnormally wide femoral neck (which is the process of bone, connecting the femoral head with the femoral shaft).

In the classification of the brachydactylies, the analysis by Bell (1951) proved highly useful. The type A brachydactylies of Bell have the shortening confined mainly to the middle phalanges. In the A1 type, the middle phalanges of all the digits are rudimentary or fused with the terminal phalanges. The proximal phalanges of the thumbs and big toes are short. Genetic Heterogeneity of Brachydactyly Type A1 BDA1B (607004) has been mapped to chromosome 5. BDA1C (615072) is caused by mutation in the GDF5 gene (601146) on chromosome 20q11. BDA1D (616849) is caused by mutation in the BMPR1B gene (603248) on chromosome 4q22.

Increased length of the big toe.

An angulation of a digit at an interphalangeal joint in the plane of the palm (finger) or sole (toe).

A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).

Abnormally low body weight.

Chiari malformation consists of a downward displacement of the cerebellar tonsils and the medulla through the foramen magnum, sometimes causing hydrocephalus as a result of obstruction of CSF outflow.

A febrile seizure is any type of seizure (most often a generalized tonic-clonic seizure) occurring with fever (at least 38 degrees Celsius) but in the absence of central nervous system infection, severe metabolic disturbance or other alternative precipitant in children between the ages of 3 months and 6 years.

A type of Developmental delay characterized by a delay in acquiring motor skills.

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.

An abnormality of skull shape characterized by a increased anterior-posterior diameter, i.e., an increased antero-posterior dimension of the skull. Cephalic index less than 76%. Alternatively, an apparently increased antero-posterior length of the head compared to width. Often due to premature closure of the sagittal suture.

A general term describing features characterized by abnormal development of bones and connective tissues.

Delayed maturation and calcification of any of the tarsal bones, seven bones of the foot comprising the calcaneus, talus, cuboid, navicular, and the cuneiform bones.

Reduced side to side width of the pelvis.

Increased width of ribs

Abnormal flatness (decreased height) of epiphyses.

The presence of an abnormally thick calvaria.

The concentration of vitamin D in the blood circulation is below the lower limit of normal.

Abnormally increased serum levels of alkaline phosphatase activity.

A tooth which does not erupt within the teeth eruption timeline and after the loss of eruption potential.

Persistence of the primary teeth beyond the age by which they normally are shed and replaced by the permanent teeth.

Forward prominence of the entire forehead, due to protrusion of the frontal bone.

Increased thickness of the lower lip, leading to a prominent appearance of the lower lip. The height of the vermilion of the lower lip in the midline is more than 2 SD above the mean. Alternatively, an apparently increased height of the vermilion of the lower lip in the frontal view (subjective).

The presence of multiple impacted teeth.

Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle.

Distance between nasal base and midline upper lip vermilion border more than 2 SD below the mean. Alternatively, an apparently decreased distance between nasal base and midline upper lip vermilion border.

The presence of multiple embedded tooth germs which have failed to erupt.

The absence of six or more teeth from the normal series by a failure to develop.

Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).