Cryptorchidism, or failure of testicular descent, is a common human congenital abnormality with a multifactorial etiology that likely reflects the involvement of endocrine, environmental, and hereditary factors. Cryptorchidism can result in infertility and increases risk for testicular tumors. Testicular descent from abdomen to scrotum occurs in 2 distinct phases: the transabdominal phase and the inguinoscrotal phase (summary by Gorlov et al., 2002).

Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.

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

The gradual reduction in girth of the finger from proximal to distal.

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

Underdevelopment (hypoplasia) of the big toe.

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

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 type of abnormal location of the ears in which the position of the ears is characterized by posterior rotation (the superior part of the ears is rotated towards the back of the head, and the inferior part of the ears towards the front).

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.

Reduced volume of the earlobe.

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

A conspicuously happy disposition, characterized by frequent smiling and laughing, which may be contextually inappropriate or unrelated to the situation.

Craniosynostosis refers to the premature closure of the cranial sutures. Primary craniosynostosis refers to the closure of one or more sutures due to abnormalities in skull development, and secondary craniosynostosis results from failure of brain growth.

An abnormality in which the mandible is mislocalised posteriorly.

Contractures of one ore more joints of the hands meaning chronic loss of joint motion due to structural changes in non-bony tissue.

Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline.

Abnormally small dimension of the Maxilla. Usually creating a malocclusion or malalignment between the upper and lower teeth or resulting in a deficient amount of projection of the base of the nose and lower midface region.

Head circumference which falls below 2 standard deviations below the mean for age and gender because of insufficient head growth after birth.

The distal interphalangeal joint and/or the proximal interphalangeal joint of the fingers or toes cannot be extended to 180 degrees by either active or passive extension.

A fixed reduction in the vertical distance between the upper and lower eyelids with short palpebral fissures.

Distance between the commissures of the mouth more than 2 SD below the mean. Alternatively, an apparently decreased width of the oral aperture (subjective).

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).

Any abnormality of the teeth.

Distance between the medial and lateral canthi is more than 2 SD below the mean for age (objective); or, apparently reduced length of the palpebral fissures.

Distance between the inner canthi more than two standard deviations above the mean (objective); or, apparently increased distance between the inner canthi.

A lack of facial expression often with staring eyes and a slightly open mouth.

Diminished length of the neck.

Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border.

Decreased density/number of eyebrow hairs.

Posterior positioning of the nasal root in relation to the overall facial profile for age.

Width of the forehead or distance between the frontotemporales is more than two standard deviations below the mean (objective); or apparently narrow intertemporal region (subjective).

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).

Distance between the hairline (trichion) and the glabella (the most prominent point on the frontal bone above the root of the nose), in the midline, more than two SD below the mean. Alternatively, an apparently decreased distance between the hairline and the glabella.

Increased breadth of the nasal bridge (and with it, the nasal root).

An abnormal configuration of the lower lip such that it is turned outward i.e., everted, with the Inner aspect of the lower lip vermilion (normally opposing the teeth) being visible in a frontal view.

Increased side-to-side width of the neck.

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.

Forward protrusion of the glabella.

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

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.

Horizontal crease or fold situated below the vermilion border of the lower lip and above the fatty pad of the chin, with the face at rest.

Upward and/or sideward growth of anterior hair.

Lack of eyelashes.

Decreased density/number of eyelashes.

Reduced density of hairs.

Underdevelopment of the nipple.

A larger than usual distance between the left and right nipple.

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).