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).

The presence of a vaginal septum, thereby creating a vaginal duplication. The septum is longitudinal in the majority of cases.

Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum.

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).

An abnormal hand posture in which the hands are clenched to fists. All digits held completely flexed at the metacarpophalangeal and interphalangeal joints. In prenatal sonography of the fetal clenched hand, the index finger overlaps a clenched fist formed by the other digits. The proximal interphalangeal articulation of the index finger is flexed and ulnarly deviated, and the thumb is adducted.

Hyperextension of the metatarsal-phalangeal joint with hyperflexion of the proximal interphalangeal (PIP) joint.

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

Visible increase in width of the hallux without an increase in the dorso-ventral dimension.

The proximal interphalangeal joint of the 3rd toe cannot be straightened actively or passively.

The proximal interphalangeal joint of the 2nd toe cannot be straightened actively or passively.

Syndactyly with fusion of toes two and three.

The presence of a stenosis (narrowing) of the aortic valve.

The heart is located in the right hand sided hemithorax. That is, there is a left-right reversal (or "mirror reflection") of the anatomical location of the heart in which the heart is locate on the right side instead of the left.

Double outlet right ventricle (DORV) is a type of ventriculoarterial connection in which both great vessels arise entirely or predominantly from the right ventricle.

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.

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

One or both of the leaflets (cusps) of the mitral valve bulges back into the left atrium upon contraction of the left ventricle.

Underdevelopment of the arch of aorta.

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).

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.

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

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).

An asymmetriy, i.e., difference in size, shape or position between the left and right ear.

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

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

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.

Mild or moderate loss of motor function accompanied by spasticity in the lower extremities. This condition is a manifestation of CENTRAL NERVOUS SYSTEM DISEASES that cause injury to the motor cortex or descending motor pathways.

Underdevelopment of the corpus callosum.

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

Dandy-Walker malformation is defined by hypoplasia and upward rotation of the cerebellar vermis and cystic dilation of the fourth ventricle. Affected individuals often have motor deficits such as delayed motor development, hypotonia, and ataxia; about half have mental retardation and some have hydrocephalus. DWM is a heterogeneous disorder. The low empiric recurrence risk of approximately 1 to 2% for nonsyndromic DWM suggests that mendelian inheritance is unlikely (summary by Murray et al., 1985).

Protrusion of abdominal contents through a defect in the abdominal wall musculature around the umbilicus. Skin and subcutaneous tissue overlie the defect.

The presence of an abnormal lateral curvature of the spine.

An abnormal osseous union (fusion) between the radius and the ulna.

A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.

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.

The union of two separately developing tooth germs typically leading to one less tooth than normal in the affected dental arch.

Dental malocclusion refers to an abnormality of the occlusion, or alignment, of the teeth and the way the upper and lower teeth fit together, resulting in overcrowding of teeth or in abnormal bite patterns.

The presence of one or more teeth additional to the normal number.

Delayed tooth eruption, which can be defined as tooth eruption more than 2 SD beyond the mean eruption age.

Persistence of the primary teeth beyond the age by which they normally are shed and replaced by the permanent teeth.

A splitting of the nasal tip. Visually assessable vertical indentation, cleft, or depression of the nasal tip.

Increase in width of the nasal tip.

Hard-palate submucous clefts are characterized by bony defects in the midline of the bony palate that are covered by the mucous membrane of the roof of the mouth. It may be possible to detect a submucous cleft hard palate upon palpation as a notch in the bony palate.

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).

Bizygomatic (upper face) and bigonial (lower face) width are both more than 2 standard deviations below the mean (objective); or, an apparent reduction in the width of the upper and lower face (subjective).

Increased density/number and/or increased diameter of eyebrow hairs.

Anterior positioning of the nasal root in comparison to the usual positioning for age.

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.

The absence of six or more teeth from the normal series by a failure to develop.

Uvula separated into two parts most easily seen at the tip.

Tooth root length more than 2 SD above mean, or subjectively apparently increased tooth root length.

Insufficient production of steroid hormones (primarily cortisol) by the adrenal glands.

Deficiency of thyroid hormone.

Absence of the globe or eyeball.

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 cataract that occurs congenitally as the result of a developmental defect, in contrast to the majority of cataracts that occur in adulthood as the result of degenerative changes of the lens.

A form of strabismus with one or both eyes deviated outward.

Glaucoma refers loss of retinal ganglion cells in a characteristic pattern of optic neuropathy usually associated with increased intraocular pressure.

Microphthalmia is an eye abnormality that arises before birth. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in these cases some remaining eye tissue is generally present. Such severe microphthalmia should be distinguished from another condition called anophthalmia, in which no eyeball forms at all. However, the terms anophthalmia and severe microphthalmia are often used interchangeably. Microphthalmia may or may not result in significant vision loss.\n\nPeople with microphthalmia may also have a condition called coloboma. Colobomas are missing pieces of tissue in structures that form the eye. They may appear as notches or gaps in the colored part of the eye called the iris; the retina, which is the specialized light-sensitive tissue that lines the back of the eye; the blood vessel layer under the retina called the choroid; or in the optic nerves, which carry information from the eyes to the brain. Colobomas may be present in one or both eyes and, depending on their size and location, can affect a person's vision.\n\nPeople with microphthalmia may also have other eye abnormalities, including clouding of the lens of the eye (cataract) and a narrowed opening of the eye (narrowed palpebral fissure). Additionally, affected individuals may have an abnormality called microcornea, in which the clear front covering of the eye (cornea) is small and abnormally curved.\n\nBetween one-third and one-half of affected individuals have microphthalmia as part of a syndrome that affects other organs and tissues in the body. These forms of the condition are described as syndromic. When microphthalmia occurs by itself, it is described as nonsyndromic or isolated.

Primary or spontaneous detachment of the retina occurs due to underlying ocular disease and often involves the vitreous as well as the retina. The precipitating event is formation of a retinal tear or hole, which permits fluid to accumulate under the sensory layers of the retina and creates an intraretinal cleavage that destroys the neurosensory process of visual reception. Vitreoretinal degeneration and tear formation are painless phenomena, and in most cases, significant vitreoretinal pathology is found only after detachment of the retina starts to cause loss of vision or visual field. Without surgical intervention, retinal detachment will almost inevitably lead to total blindness (summary by McNiel and McPherson, 1971).

A coloboma of the iris.

A congenital abnormality of the cornea in which the cornea and the anterior segment of the eye are smaller than normal. The horizontal diameter of the cornea does not reach 10 mm even in adulthood.

Persistence of the hyaloid artery, which is the embryonic artery that runs from the optic disc to the posterior lens capsule may persist; the site of attachment may form an opacity. The hyaloid artery is a branch of the ophthalmic artery, and usually regresses completely before birth. This features results from a failure of regression of the hyaloid vessel, which supplies the primary vitreous during embryogenesis and normally regresses in the third trimester of pregnancy, leading to a particular form of posterior cataract.

Atrophy of the eyeball with blindness and decreased intraocular pressure due to end-stage intraocular disease.

Loss of visual acuity (implying that vision was better at a certain time point in life). Otherwise the term reduced visual acuity should be used (or a subclass of that).