The distal and proximal transverse palmar creases are merged into a single transverse palmar crease.

Clinodactyly refers to a bending or curvature of the fifth finger in the radial direction (i.e., towards the 4th finger).

Proximal mislocalization of the thumb.

A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum.

Aortic valve disease-2 (AOVD2) is characterized by bicuspid aortic valve (BAV) and dilation of the ascending aorta. Calcification of the valve and the aorta has been observed, and some patients exhibit coarctation of the aorta (Tan et al., 2012; Luyckx et al., 2019; Park et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of aortic valve disease, see AOVD1 (109730).

Enlargement or increased size of the heart left ventricle.

A type of transposition of the great arteries (TGA) in which aorta is in front of and primarily to the right of the pulmonary artery. This is the most common kind of TGA.

Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.

Underdevelopment of the external ear.

Upper insertion of the ear to the scalp below an imaginary horizontal line drawn between the inner canthi of the eye and extending posteriorly to the ear.

A decreased magnitude of the sensory perception of sound.

A condition in which the helix is folded over to a greater degree than normal. That is, excessive curling of the helix edge, whereby the free edge is parallel to the plane of the ear.

Laterally protruding ear that lacks antihelical folding (including absence of inferior and superior crura).

Angle formed by the plane of the ear and the mastoid bone greater than the 97th centile for age (objective); or, outer edge of the helix more than 2 cm from the mastoid at the point of maximum distance (objective).

Mild intellectual disability is defined as an intelligence quotient (IQ) in the range of 50-69.

The corpus callosum is the largest fiber tract in the central nervous system and the major interhemispheric fiber bundle in the brain. Formation of the corpus callosum begins as early as 6 weeks' gestation, with the first fibers crossing the midline at 11 to 12 weeks' gestation, and completion of the basic shape by age 18 to 20 weeks (Schell-Apacik et al., 2008). Agenesis of the corpus callosum (ACC) is one of the most frequent malformations in brain with a reported incidence ranging between 0.5 and 70 in 10,000 births. ACC is a clinically and genetically heterogeneous condition, which can be observed either as an isolated condition or as a manifestation in the context of a congenital syndrome (see MOLECULAR GENETICS and Dobyns, 1996). Also see mirror movements-1 and/or agenesis of the corpus callosum (MRMV1; 157600). Schell-Apacik et al. (2008) noted that there is confusion in the literature regarding radiologic terminology concerning partial absence of the corpus callosum, where various designations have been used, including hypogenesis, hypoplasia, partial agenesis, or dysgenesis.

Underdevelopment of the corpus callosum.

Colpocephaly is an anatomic finding in the brain manifested by occipital horns that are disproportionately enlarged in comparison with other parts of the lateral ventricles.

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

Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior.

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

A mild delay in the achievement of motor or mental milestones in the domains of development of a child.

Vertical bony ridge positioned in the midline of the forehead.

Generalized muscular hypotonia (abnormally low muscle tone).

An abnormal horizontal axis orientation of the crus of the helix. That is, the main axis of the crus of the helix is perpendicular to the medial longitudinal axis of the ear, instead of sloping inferoposteriorly.

The palpebral fissure inclination is more than two standard deviations below the mean.

Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).

Anteriorly-facing nostrils viewed with the head in the Frankfurt horizontal and the eyes of the observer level with the eyes of the subject. This gives the appearance of an upturned nose (upturned nasal tip).

More pronounced paramedian peaks and median notch of the Cupid's bow.

Distance between the philtral ridges, measured just above the vermilion border, more than 2 standard deviations above the mean, or alternatively, an apparently increased distance between the ridges of the philtrum.

Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.

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

Small indentation anterior to the insertion of the ear.

Underdevelopment of a fingernail.

The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).