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).

Lack of the ability to control the urinary bladder leading to involuntary urination at an age where control of the bladder should already be possible.

Hypoplasia of the kidney.

Weakness of the muscles of the legs.

Protruding heel bone, or calcaneus.

Syndactyly with fusion of toes two and three.

Any structural anomaly of the heart.

Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum.

A narrowing of the right ventricular outflow tract that can occur at the pulmonary valve (valvular stenosis), below the pulmonary valve (infundibular stenosis), or above the pulmonary valve (supravalvar stenosis).

Smaller than normal size according to sex and gestational age related norms, defined as a weight below the 10th percentile for the gestational age.

A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).

Abnormally low body weight.

Difficulty in swallowing.

A reduced desire to eat.

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

Bruxism is characterized by the grinding of the teeth including the clenching of the jaw and typically occur during sleep, but also can occur while the affected individual is awake.

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).

Cerebral palsy describes a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to nonprogressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication, and behavior, by epilepsy, and by secondary musculoskeletal problems.

A series of rhythmic and involuntary muscle contractions (at a frequency of about 5 to 7 Hz) that occur in response to an abruptly applied and sustained stretch.

Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.

An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk.

Echolalia is the automatic imitative repetition of sounds, words, or phrases in the absence of explicit awareness. The repeated words or phrases are typically odd or used in a non-social manner. These can be words or phrases that the affected individual has heard or invented.

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

Moderate mental retardation is defined as an intelligence quotient (IQ) in the range of 35-49.

Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements.

Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course.

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.

An unintentional, oscillating to-and-fro muscle movement about a joint axis.

An extra-parenchymal and intra-arachnoidal collection of fluid with a composition similar to that of cerebrospinal fluid.

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

Functional neurological abnormalities related to dysfunction of the pyramidal tract.

A neurological condition related to lesions of the basal ganglia leading to typical abnormalities including akinesia (inability to initiate changes in activity and perform volitional movements rapidly and easily), muscular rigidity (continuous contraction of muscles with constant resistance to passive movement), chorea (widespread arrhythmic movements of a forcible, rapid, jerky, and restless nature), athetosis (inability to sustain the muscles of the fingers, toes, or other group of muscles in a fixed position), and akathisia (inability to remain motionless).

A type of ataxia characterized by the inability to carry out movements with the correct range and motion across the plane of more than one joint related to incorrect estimation of the distances required for targeted movements.

A tremor present when the limbs are active, either when outstretched in a certain position or throughout a voluntary movement.

A type of tremors that is triggered by holding a limb in a fixed position.

Abnormal coordination of muscles involved in speech.

A type of ataxia characterized by the impairment of the ability to perform rapidly alternating movements, such as pronating and supinating his or her hand on the dorsum of the other hand as rapidly as possible.

Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum.

An unintentional, oscillating to-and-fro muscle movement affecting head movement.

The patient stands with the feet placed together and balance and is asked to close his or her eyes. A loss of balance upon eye closure is a positive Romberg sign and is interpreted as indicating a deficit in proprioception.

A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.

Cerebellar hypoplasia is a descriptive term implying a cerebellum with a reduced volume, but a normal shape and is stable over time.

Focal impaired awareness seizure (or focal seizure with impaired or lost awareness) is a type of focal-onset seizure characterized by some degree (which may be partial) of impairment of the person's awareness of themselves or their surroundings at any point during the seizure.

Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering.

Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting.

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.

Incapability to ambulate.

The term gait disturbance can refer to any disruption of the ability to walk.

Myokymia consists of involuntary, fine, continuous, undulating contractions that spread across the affected striated muscle.

Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.

Wasting (atrophy) of the vermis of cerebellum.

A kind of ataxia that affects movements of the extremities.

A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall.

An abnormality of the function of the electrical signals with which peripheral nerve cells communicate with each other or with muscles.

An abnormal gait pattern in which persons stand and walk with their feet spaced widely apart. This is often a component of cerebellar ataxia.

A specific learning disability involving mathematics and arithmetic.

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

Loss of developmental skills, as manifested by loss of developmental milestones.

Inability to walk in a person who previous had the ability to walk.

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.

Underdevelopment of the vermis of cerebellum.

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

A type of dysmetria involving the limbs.

Diffuse unlocalised atrophy affecting the cerebellum.

Absence or underdevelopment of the vermis of cerebellum.

Long-tract signs refer to symptoms that are attributable to the involvement of the long fiber tracts in the spinal cord, which connect the spinal cord to the brain and mediate spinal and motor functions.

Tendon reflexes that are noticeably more active than usual (conventionally denoted 3+ on clinical examination). Brisk reflexes may or may not indicate a neurological lesion. They are distinguished from hyperreflexia by the fact that hyerreflexia is characterized by hyperactive repeating (clonic) reflexes, which are considered to be always abnormal.

Tremor of the trunk in an anterior-posterior plane at 3-4 Hz.

Reduced ability to walk in a straight line while placing the feet heel to toe.

Ocular motor apraxia is a deficiency in voluntary, horizontal, lateral, fast eye movements (saccades) with retention of slow pursuit movements. The inability to follow objects visually is often compensated by head movements. There may be decreased smooth pursuit, and cancelation of the vestibulo-ocular reflex.

Increased intensity of muscle tendon reflexes in jaw.

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.

Diffuse, bilateral and recently also unilateral or focal localization spike-wave occurring in slow sleep or non-rapid eye movement sleep.

An anomaly identified by motor evoked potentials (MEPs). MEPs are measured following single-pulse or repetitive transcranial magnetic stimulation and can be used for the assessment of the excitability of the motor cortex and the integrity of conduction along the central and peripheral motor pathways.

A type of motor delay characterized by a delay in acquiring the ability to control the fingers and hands.

The presence of cerebellar signs and symptoms such as lack of balance associated with quadrupedal gait (locomotion on all four extremities with a 'bear-like' gait with the legs held straight).

The presence of atrophy (wasting) of the cerebrum, also known as the telencephalon, the largest and most highly developed part of the human brain.

A failure to achieve the ability to stand up at an appropriate developmental stage. Most children begin to walk alone at 11 to 15 months of age. On average, children can stand while holding on at the age of 9 to 10 months, can pull up to stand and walk with one hand being held at 12 months, and can stand alone and walk well at 18 months.

A failure to achieve the ability to sit at an appropriate developmental stage. Most children sit with support at 6 months of age and sit steadily without support at 9 months of age.

A type of kinetic tremor that occurs during target directed movement is called intention tremor. That is, an oscillatory cerebellar ataxia that tends to be absent when the limbs are inactive and during the first part of voluntary movement but worsening as the movement continues and greater precision is required (e.g., in touching a target such as the patient's nose or a physician's finger).

Atrophy of the cortex of the cerebrum.

A failure to achieve the ability to crawl at an appropriate developmental stage. Normal infant motor development is marked by a series of postural milestones including learning to crawl on hands and knees between the ages of 6 and 10 months.

A failure to achieve the ability to walk with support (cruise) at an appropriate developmental stage.

Any abnormality of eye contact behavior. We define eye contact as a form of nonverbal communication between two individuals who are facing each other in which an individual directs the eyes towards the eyes or face of the other individual. Eye contact occurs frequently and voluntarily during face-to-face verbal communication. The duration and frequency of eye contact that is interpreted to be appropriate may follow social and situational norms.

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

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.

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

A lack of strength of the proximal muscles.

A phenomenon whereby patients are not able to stand up without the use of the hands owing to weakness of the proximal muscles of the lower limbs.

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

Atrophy of the peroneous muscles, peroneus longus (also known as Fibularis longus), Peroneus brevis (also known as fibularis brevis, and Peroneus tertius (also known as fibularis tertius).

Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months.

Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period and affecting the entire musculature.

Generalized muscular hypotonia (abnormally low muscle tone).

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

Two-sided or bilateral weakness of the muscles of facial expression and eye closure.

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

Habitual flow of saliva out of the mouth.

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).

Maxillary teeth cover the mandibular teeth when biting to an increased degree. The feature is defined as a vertical overlap of the maxillary incisors over the mandibular incisors that exceeds 2 mm.

This is a description previously used to describe a facial form characterized by a short, upturned nose, wide mouth, widely spaced eyes, and full cheeks. Because of the imprecision in this definition it is preferable to describe these features precisely. This term is retained because it was often used in the past, but it should not be used for new annotations.

The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age.

An abnormal morphology (form) of the face or its components.

Distance between subnasale and pronasale more than two standard deviations above the mean, or alternatively, an apparently increased anterior protrusion of the nasal tip.

Accentuated, prominent philtral ridges giving rise to an exaggerated groove in the midline between the nasal base and upper vermillion border.

A forehead with abnormal flatness.

A thickening of the skin thickness in the posterior aspect of the fetal neck. A nuchal fold (NF) measurement is obtained in a transverse section of the fetal head at the level of the cavum septum pellucidum and thalami, angled posteriorly to include the cerebellum. The measurement is taken from the outer edge of the occiput bone to the outer skin limit directly in the midline. An NF measurement greater than 5 mm at 14 to 17+6 weeks of gestation, or 6 mm at 18 to 28 weeks has been associated with a markedly increased risk for Down syndrome.

PAX6-related aniridia occurs either as an isolated ocular abnormality or as part of the Wilms tumor-aniridia-genital anomalies-retardation (WAGR) syndrome. Aniridia is a pan ocular disorder affecting the cornea, iris, intraocular pressure (resulting in glaucoma), lens (cataract and lens subluxation), fovea (foveal hypoplasia), and optic nerve (optic nerve coloboma and hypoplasia). Individuals with aniridia characteristically show nystagmus and impaired visual acuity (usually 20/100 - 20/200); however, milder forms of aniridia with subtle iris architecture changes, good vision, and normal foveal structure do occur. Other ocular involvement may include strabismus and occasionally microphthalmia. Although the severity of aniridia can vary between and within families, little variability is usually observed in the two eyes of an affected individual. WAGR syndrome. The risk for Wilms tumor is 42.5%-77%; of those who develop Wilms tumor, 90% do so by age four years and 98% by age seven years. Genital anomalies in males can include cryptorchidism and hypospadias (sometimes resulting in ambiguous genitalia), urethral strictures, ureteric abnormalities, and gonadoblastoma. While females typically have normal external genitalia, they may have uterine abnormalities and streak ovaries. Intellectual disability (defined as IQ <74) is observed in 70%; behavioral abnormalities include attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, anxiety, depression, and obsessive-compulsive disorder. Other individuals with WAGR syndrome can have normal intellect without behavioral problems.

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).

A form of strabismus with one or both eyes turned inward ('crossed') to a relatively severe degree, usually defined as 10 diopters or more.

An abnormality of refraction characterized by the ability to see objects in the distance clearly, while objects nearby appear blurry.

A cone-shaped deformity of the cornea characterized by the presence of corneal distortion secondary to thinning of the apex.

Abnormal (non-physiological) constriction of the pupil.

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.

An abnormal white reflection from the pupil rather than the usual black reflection.

An abnormality of eye movement characterized by impairment of fast (saccadic) eye movements.

A form of nystagmus in which the eyeball makes rotary motions around the axis.

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

Congenital underdevelopment of the iris.

An abnormally slow velocity of the saccadic eye movements.

An abnormality of eye movement characterized by impaired smooth-pursuit eye movements.

Horizontal nystagmus made apparent by looking to the right or to the left.

An abnormally slow velocity of horizontal saccadic eye movements.

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.

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

Horizontal nystagmus dating from or present at birth.

Nystagmus made apparent by looking to the right or to the left.