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).

Severe distention of the kidney with dilation of the renal pelvis and calices.

A developmental anomaly characterized by the presence of two, instead of one, ureter connecting a kidney to the bladder.

The presence of a bicornuate uterus.

Midline indentation or cleft of the scrotum.

Agenesis, that is, failure of the kidney to develop during embryogenesis and development.

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.

Superior margin of the scrotum superior to the base of the penis.

A fluid filled sac in the kidney.

Congenital vertical talus (CVT), also known as 'rocker-bottom foot' deformity, is a dislocation of the talonavicular joint characterized by vertical orientation of the talus with a rigid dorsal dislocation of the navicular, equinus deformity of the calcaneus, abduction deformity of the forefoot, and contracture of the soft tissues of the hind- and mid-foot. This condition is usually associated with multiple other congenital deformities and only rarely is an isolated deformity with familial occurrence (summary by Levinsohn et al., 2004). The condition is transmitted in an autosomal dominant pattern of inheritance, and sometimes shows incomplete penetrance and variable expressivity. There may be a broad spectrum of deformities, including flatfoot, talipes equinovarus (TEV or clubfoot), cavus foot, metatarsus adductus, and even hypoplasia of the tibia (summary by Dobbs et al., 2006).

The distal and proximal transverse palmar creases are merged into a single transverse palmar crease.

Hypoplasia (congenital reduction in size) of the thumb.

Short distance from the end of the finger to the most distal interphalangeal crease or the distal interphalangeal joint flexion point. That is, hypoplasia of one or more of the distal phalanx of finger.

Proximal mislocalization of the thumb.

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.

The term large for gestational age applies to babies whose birth weight lies above the 90th percentile for that gestational age.

Congenital absence of the anus, i.e., the opening at the bottom end of the intestinal tract.

A developmental defect resulting in complete obliteration of the lumen of the esophagus such that the esophagus ends in a blind pouch rather than connecting to the stomach.

The disorder described by Hirschsprung (1888) and known as Hirschsprung disease or aganglionic megacolon is characterized by congenital absence of intrinsic ganglion cells in the myenteric (Auerbach) and submucosal (Meissner) plexuses of the gastrointestinal tract. Patients are diagnosed with the short-segment form (S-HSCR, approximately 80% of cases) when the aganglionic segment does not extend beyond the upper sigmoid, and with the long-segment form (L-HSCR) when aganglionosis extends proximal to the sigmoid (Amiel et al., 2008). Total colonic aganglionosis and total intestinal HSCR also occur. Genetic Heterogeneity of Hirschsprung Disease Several additional loci for isolated Hirschsprung disease have been mapped. HSCR2 (600155) is associated with variation in the EDNRB gene (131244) on 13q22; HSCR3 (613711) is associated with variation in the GDNF gene (600837) on 5p13; HSCR4 (613712) is associated with variation in the EDN3 gene (131242) on 20q13; HSCR5 (600156) maps to 9q31; HSCR6 (606874) maps to 3p21; HSCR7 (606875) maps to 19q12; HSCR8 (608462) maps to 16q23; and HSCR9 (611644) maps to 4q31-q32. HSCR also occurs as a feature of several syndromes including the Waardenburg-Shah syndrome (277580), Mowat-Wilson syndrome (235730), Goldberg-Shprintzen syndrome (609460), and congenital central hypoventilation syndrome (CCHS; 209880). Whereas mendelian modes of inheritance have been described for syndromic HSCR, isolated HSCR stands as a model for genetic disorders with complex patterns of inheritance. Isolated HSCR appears to be of complex nonmendelian inheritance with low sex-dependent penetrance and variable expression according to the length of the aganglionic segment, suggestive of the involvement of one or more genes with low penetrance. The development of surgical procedures decreased mortality and morbidity, which allowed the emergence of familial cases. HSCR occurs as an isolated trait in 70% of patients, is associated with chromosomal anomaly in 12% of cases, and occurs with additional congenital anomalies in 18% of cases (summary by Amiel et al., 2008).

Meckel's diverticulum is a congenital diverticulum located in the distal ileum.

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.

A developmental defect resulting in complete obliteration of the duodenal lumen, that is, an abnormal closure of the duodenum.

The presence of pancreatic tissue outside the normal pancreas, in many cases along the foregut and proximal midgut.

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 helix. The helix is the outer rim of the ear that extends from the insertion of the ear on the scalp (root) to the termination of the cartilage at the earlobe.

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.

A defect of development of the brain characterized by congenital absence of the part of the brain that includes the olfactory bulbs, tracts, and other structures associated with the sense of smell.

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.

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.

Contractures of one ore more joints of the hands meaning chronic loss of joint motion due to structural changes in non-bony tissue.

Ribs with a reduced diameter.

The distal interphalangeal joint and/or the proximal interphalangeal joint of the fingers or toes cannot be extended to 180 degrees by either active or passive extension.

An omphalocele is an abdominal wall defect limited to an open umbilical ring, and is characterized by the herniation of membrane-covered internal organs into the open base of the umbilical cord. Omphalocele is distinguished from gastroschisis (230750), in which the abdominal wall defect is located laterally to a normally closed umbilical ring with herniation of organs that are uncovered by membranes (summary by Bugge, 2010). On the basis of clinical manifestations, epidemiologic characteristics, and the presence of additional malformations, Yang et al. (1992) concluded that omphalocele and gastroschisis are casually and pathogenetically distinct abdominal wall defects. Omphalocele can be a feature of genetic disorders, such as Beckwith-Wiedemann syndrome (130650) and the Shprintzen-Goldberg syndrome (182210).

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

Increased width of ribs

A congenital brain malformation typically characterized by incomplete formation of the cerebellar vermis, dilation of the fourth ventricle, and enlargement of the posterior fossa. In layman's terms, Dandy Walker malformation is a cyst in the cerebellum (typically symmetrical) that is involved with the fourth ventricle. This may interfere with the ability to drain cerebrospinal fluid from the brain, resulting in hydrocephalus. Dandy Walker cysts are formed during early embryonic development, while the brain forms. The cyst in the cerebellum typically has several blood vessels running through it connecting to the brain, thereby prohibiting surgical removal.

Congenital absence of the left half of the diaphragm.

Accumulation of excessive amounts of lymphatic fluid (chyle) in the pleural cavity.

A congenital abnormality in which the lung parenchyma is not fully developed. It may be associated with other congenital abnormalities.

Polysplenia is a congenital disease manifested by multiple small accessory spleens.

A fixed reduction in the vertical distance between the upper and lower eyelids with short palpebral fissures.

A gap or groove in the upper lip. This is a congenital defect resulting from nonfusion of tissues of the lip during embryonal development.

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

Diminished length of the neck.

Triangular appearance of the oral aperture with the apex in the midpoint of the upper vermilion and the lower vermilion forming the base.

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).

Absence of fine and sharp appearance of brows, nose, lips, mouth, and chin, usually because of rounded and heavy features or thickened skin with or without thickening of subcutaneous and bony tissues.

Increased breadth of the nasal bridge (and with it, the nasal root).

Increased side-to-side width of the neck.

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.

Reduction in the vertical distance between the upper and lower eyelids.

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).

A nail that is diminished in length and width, i.e., underdeveloped nail.

Congenital anonychia is defined as the absence of fingernails and toenails. Anonychia and its milder phenotypic variant, hyponychia, usually occur as a feature of genetic syndromes, in association with significant skeletal and limb anomalies. Isolated nonsyndromic congenital anonychia/hyponychia is a rare entity that usually follows autosomal recessive inheritance with variable expression, even within a given family. The nail phenotypes observed range from no nail field to a nail field of reduced size with an absent or rudimentary nail (summary by Bruchle et al., 2008). This form of nail disorder is referred to here as nonsyndromic congenital nail disorder-4 (NDNC4). For a list of other nonsyndromic congenital nail disorders and a discussion of genetic heterogeneity, see NDNC1 (161050).

A soft tissue prominence of the ventral aspects of the fingertips. The term "persistent fetal fingertip pads" is often used as a synonym, but should better not be used because it implies knowledge of history of the patient which often does not exist.

Excess facial hair.

The presence of excess amniotic fluid in the uterus during pregnancy.

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).

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.

Reduced transparency of the stroma of cornea.