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).

In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.

Failure of the foramen ovale to seal postnatally, leaving a potential conduit between the left and right cardiac atria.

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

A deficiency or slowing down of growth pre- and postnatally.

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

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.

An abnormality of the pinna, which is also referred to as the auricle or external ear.

A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.

A seizure is an intermittent abnormality of nervous system physiology characterised by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Severe mental retardation is defined as an intelligence quotient (IQ) in the range of 20-34.

Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.

Underdevelopment of the corpus callosum.

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.

Incapability to ambulate.

Difficulty in looking at another person in the eye.

An abnormality of myelination of nerves in the central nervous system.

Developmental hypoplasia of the mandible.

A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move.

Asymmetric head shape, which is usually a combination of unilateral occipital flattening with ipsilateral frontal prominence, leading to rhomboid cranial shape.

Difficulty to maintain correct position of the head while standing or sitting.

Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period.

Head circumference below 2 standard deviations below the mean for age and gender.

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).

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.

Interalar distance more than two standard deviations above the mean for age, i.e., an apparently increased width of the nasal base and alae.

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).

Facial contour, as viewed from the front, triangular in shape, with breadth at the temples and tapering to a narrow chin.

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

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.

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.

Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.

An eye that is more deeply recessed into the plane of the face than is typical.

A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye.