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).

Clubfoot is a congenital limb deformity defined as fixation of the foot in cavus, adductus, varus, and equinus (i.e., inclined inwards, axially rotated outwards, and pointing downwards) with concomitant soft tissue abnormalities (Cardy et al., 2007). Clubfoot may occur in isolation or as part of a syndrome (e.g., diastrophic dysplasia, 222600). Clubfoot has been reported with deficiency of long bones and mirror-image polydactyly (Gurnett et al., 2008; Klopocki et al., 2012).

A type of knee joint contracture in which the knee is in a fixed bent (flexed) configuration such that it cannot be straightened actively or passively.

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

Syndactyly with fusion of toes one to four.

Syndactyly with fusion of fingers four and five.

Syndactyly with fusion of toes two and three.

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

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

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

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).

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

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.

A cyst occurring within the choroid plexus within a cerebral ventricle.

Underdevelopment of the corpus callosum.

The presence of developmental dysplasia of the cerebral cortex.

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

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.

Hypsarrhythmia is abnormal interictal high amplitude waves and a background of irregular spikes. There is continuous (during wakefulness), high-amplitude (>200 Hz), generalized polymorphic slowing with no organized background and multifocal spikes demonstrated by electroencephalography (EEG).

The Premie-Neuro and the Dubowitz Neurological Examination score head lag in the same manner. Scoring for both is as follows

A type of motor delay characterized by a delay in acquiring the ability to control the large muscles of the body for walking, running, sitting, and crawling.

Complete lack of development of speech and language abilities.

Nodules of heterotopia along the ventricular walls. There can be a single nodule or a large number of nodules, they can exist on either or both sides of the brain at any point along the higher ventricle margins, they can be small or large, single or multiple.

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.

Infantile spasms represent a subset of "epileptic spasms". Infantile Spasms are epileptic spasms starting in the first year of life (infancy).

Delayed myelination in the central nervous system.

A generalized non-motor (absence) seizure is a type of a type of dialeptic seizure that is of electrographically generalized onset. It is a generalized seizure characterized by an interruption of activities, a blank stare, and usually the person will be unresponsive when spoken to. Any ictal motor phenomena are minor in comparison to these non-motor features.

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.

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 limitation in the passive range of motion of the elbow resulting from loss of elasticity in the periarticular tissues owing to structural changes of non-bony tissues, such as muscles, tendons, ligaments, joint capsules or skin.

A form of developmental hypoplasia of the mandible in which the mandible is mislocalised posteriorly.

Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.

Chronic loss of joint motion of the proximal interphalangeal joint of the 2nd finger due to structural changes in non-bony tissue.

Chronic loss of joint motion of the proximal interphalangeal joint of the 3rd finger due to structural changes in non-bony tissue.

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

Pierre Robin sequence is a craniofacial anomaly comprising mandibular hypoplasia, cleft secondary palate, and glossoptosis leading to life-threatening obstructive apnea and feeding difficulaties during the neonatal period (summary by Tan et al., 2013).

Changes in alignment of teeth in the dental arch

The facial appearance is more circular than usual as viewed from the front.

Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (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 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.

Cleft palate is a developmental defect of the palate resulting from a failure of fusion of the palatine processes and manifesting as a separation of the roof of the mouth (soft and hard palate).

An eye that is protruding anterior to the plane of the face to a greater extent than is typical.

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).

Nearsightedness, also known as myopia, is an eye condition that causes blurry distance vision. People who are nearsighted have more trouble seeing things that are far away (such as when driving) than things that are close up (such as when reading or using a computer). If it is not treated with corrective lenses or surgery, nearsightedness can lead to squinting, eyestrain, headaches, and significant visual impairment.\n\nNearsightedness usually begins in childhood or adolescence. It tends to worsen with age until adulthood, when it may stop getting worse (stabilize). In some people, nearsightedness improves in later adulthood.\n\nFor normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. People who are nearsighted typically have eyeballs that are too long from front to back. As a result, light entering the eye is focused too far forward, in front of the retina instead of on its surface. It is this change that causes distant objects to appear blurry. The longer the eyeball is, the farther forward light rays will be focused and the more severely nearsighted a person will be.\n\nNearsightedness is measured by how powerful a lens must be to correct it. The standard unit of lens power is called a diopter. Negative (minus) powered lenses are used to correct nearsightedness. The more severe a person's nearsightedness, the larger the number of diopters required for correction. In an individual with nearsightedness, one eye may be more nearsighted than the other.\n\nEye doctors often refer to nearsightedness less than -5 or -6 diopters as "common myopia." Nearsightedness of -6 diopters or more is commonly called "high myopia." This distinction is important because high myopia increases a person's risk of developing other eye problems that can lead to permanent vision loss or blindness. These problems include tearing and detachment of the retina, clouding of the lens (cataract), and an eye disease called glaucoma that is usually related to increased pressure within the eye. The risk of these other eye problems increases with the severity of the nearsightedness. The term "pathological myopia" is used to describe cases in which high myopia leads to tissue damage within the eye.

Nystagmus consisting of horizontal to-and-fro eye movements.

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

A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression.

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

A manifest or latent ocular deviation in which one or both eyes tends to deviate temporally.