Divergence of the longitudinal axis of the hand at the wrist in a posterior (ulnar) direction (i.e., towards the little finger).

Increased thumb width without increased dorso-ventral dimension.

An abnormally increased extension of the knee joint, so that the knee can bend backwards.

Bilateral clubfoot deformity.

A widely spaced gap between the first toe (the great toe) and the second toe.

Difficulty in swallowing.

A benign (noncancerous) tumorlike malformation made up of an abnormal mixture of cells and tissues that originates in the tongue.

Underdevelopment of the external ear.

A decreased magnitude of the sensory perception of sound.

Discontinuity in the convexity of the inferior margin of the lobe.

Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds).

Heterotopia or neuronal heterotopia are macroscopic clusters of misplaced neurons (gray matter), most often situated along the ventricular walls or within the subcortical white matter.

Pallister-Hall-like syndrome (PHLS) is a pleiotropic autosomal recessive disorder characterized by phenotypic variability. Patients exhibit postaxial polydactyly as well as hypothalamic hamartoma, cardiac and skeletal anomalies, and craniofacial dysmorphisms. Hirschsprung disease has also been observed (Rubino et al., 2018; Le et al., 2020). Pallister-Hall syndrome (146510) is an autosomal dominant disorder with features overlapping those of PHLS, caused by mutation in the GLI3 gene (165240).

A partial failure of the development of the corpus callosum.

A degree of language development that is significantly below the norm for a child of a specified age.

Underdevelopment of the vermis of cerebellum.

Cystic collection (sac-like, fluid containing pocket of membranous tissue) located in the interhemispheric fissure, with or without communication with the ventricular system.

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

An increase in size of the ventricular system of the brain.

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.

A reduced ability to participate in the back-and-forth flow of social interaction appropriate to culture and developmental level, which is normally characterized by an influence of the behavior of one person on the behavior of another person. This results in difficulty interacting with others through emotional, physical, or verbal communication.

An abnormally thin corpus callous, due to atrophy, hypoplasia or agenesis. This term is intended to be used in situations where it is not known if thinning of the corpus callosum (for instance, as visualized by magnetic resonance tomography) is due to abnormal development (e.g. a leukodystrophy) or atrophy following normal development (e.g. neurodegeneration).

Developmental hypoplasia of the mandible.

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.

Increased length and width of the tongue.

An abnormally increased height of the forehead.

Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective).

An abnormal difference between the left and right sides of the face.

Reduced distance from the anterior border of the naris to the subnasale.

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

A cutaneous indentation resulting from tethering of the skin to underlying structures (bone) of the intergluteal cleft.

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).

A notch or cleft of the retina.