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).

A unilateral form of agenesis of the kidney.

A bilateral form of agenesis of the kidney.

Underdevelopment of the urinary bladder.

A type of chronic kidney disease with mildly reduced glomerular filtration rate (GFR 60-89 mL/min/1.73 m2).

A degree of kidney failure severe enough to require dialysis or kidney transplantation for survival characterized by a severe reduction in glomerular filtration rate (less than 15 ml/min/1.73 m2) and other manifestations including increased serum creatinine.

An increase in amplitude of waves returned in ultrasonography of the kidney, which is generally displayed as increased brightness of the signal.

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 developmental defect characterized by reduced length of the first metacarpal (long bone) of the hand.

Underdevelopment (hypoplasia) of the big toe.

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.

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

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

The commonest form of tetralogy of Fallot characterized by pulmonary stenosis, overriding aorta, ventricular septum defect, and right ventricular hypertrophy, without pulmonary atresia, absent pulmonary valve, atrioventricular canal defect or absent subarterial conus.

Slow or limited growth after birth.

An abnormality of the intestinal rotation and fixation that normally occurs during the development of the gut. This can lead to volvulus, or twisting of the intestine that causes obstruction and necrosis.

Anterior malposition of the anus.

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

A type of hearing loss resulting from a combination of conductive hearing impairment and sensorineural hearing impairment.

Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.

The corpus callosum is the largest fiber tract in the central nervous system and the major interhemispheric fiber bundle in the brain. Formation of the corpus callosum begins as early as 6 weeks' gestation, with the first fibers crossing the midline at 11 to 12 weeks' gestation, and completion of the basic shape by age 18 to 20 weeks (Schell-Apacik et al., 2008). Agenesis of the corpus callosum (ACC) is one of the most frequent malformations in brain with a reported incidence ranging between 0.5 and 70 in 10,000 births. ACC is a clinically and genetically heterogeneous condition, which can be observed either as an isolated condition or as a manifestation in the context of a congenital syndrome (see MOLECULAR GENETICS and Dobyns, 1996). Also see mirror movements-1 and/or agenesis of the corpus callosum (MRMV1; 157600). Schell-Apacik et al. (2008) noted that there is confusion in the literature regarding radiologic terminology concerning partial absence of the corpus callosum, where various designations have been used, including hypogenesis, hypoplasia, partial agenesis, or dysgenesis.

Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds).

Stenosis of the cerebral aqueduct (also known as the mesencephalic duct, aqueductus mesencephali, or aqueduct of Sylvius), which connects the third cerebral ventricle in the diencephalon to the fourth ventricle, which is between the pons and cerebellum.

A partial failure of the development of the corpus callosum.

Involuntary movements of one hand that accompany and mirror intentional movements of the opposite hand.

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.

Underdevelopment of the vermis of cerebellum.

Underdevelopment of the pons.

An increase in size of the ventricular system of the brain.

An abnormal anatomical location of the posterior lobe of the hypophysis, also known as the neurohypophysis. The posterior pituitary is normally present in the dorsal portion of the sella turcica, but when ectopic is usually near the median eminence. This defect is likely to be due to abnormal migration during embryogenesis.

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.

An abnormally thin corpus callous, due to atrophy, hypoplasia or agenesis. This term is intended to be used in situations where it is not known if thinning of the corpus callosum (for instance, as visualized by magnetic resonance tomography) is due to abnormal development (e.g. a leukodystrophy) or atrophy following normal development (e.g. neurodegeneration).

Developmental hypoplasia of the mandible.

Abnormally high level of conjugated bilirubin in the blood.

Recurrent episodes of decreased concentration of glucose in the blood.

Width of the forehead or distance between the frontotemporales is more than two standard deviations above the mean (objective); or apparently increased distance between the two sides of the forehead.

Distance between the philtral ridges, measured just above the vermilion border, more than 2 standard deviations above the mean, or alternatively, an apparently increased distance between the ridges of the philtrum.

Increased height of the central portion of the eyebrow, forming a crescent, semicircular, or inverted U shape.

A complete or near-complete lack of amniotic fluid surrounding a fetus. This finding can be observed sonographically in the third trimesters if the deepest pocket of amniotic fluid is less than or equal to 2 cm.

A type of hypothyroidism due to an insufficient stimulation of an otherwise normal thyroid gland. Central hypothyroidism is caused by either pituitary (secondary hypothyroidism) or hypothalamic (tertiary hypothyroidism) defects.

Abnormally reduced concentration of cortisol in the blood.

The concentration of corticotropin, also known as adrenocorticotropic hormone (ACTH), is below the lower limit of normal in the blood circulation.

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

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.

Loss of iris tissue (atrophy)