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).

Epispadias is a urogenital malformation characterized by the failure of the urethral tube to tubularize on the dorsal aspect. Unlike in hypospadias, where the meatus is on the ventral aspect, children with epispadias have a wide-open urethral plate on the dorsum. It is commonly seen as a component in the spectrum of bladder exstrophy-epispadias-complex. Isolated epispadias constitutes less than 10 percent of the total cases of epispadias.

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).

Supernumerary digits located at the ulnar side of the hand (that is, on the side with the fifth finger).

The legs angle inward, such that the knees are close together and the ankles far apart.

Polydactyly of the foot most commonly refers to the presence of six toes on one foot. Postaxial polydactyly affects the lateral ray and the duplication may range from a well-formed articulated digit to a rudimentary digit.

The presence of osteophytes (bone spurs), i.e., of bony projections originating from the acetabulum.

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.

Complete absence of the interatrial septum with common atrioventricular valve and two atrioventricular connections.

A type of disproportionate short stature characterized by a short limbs but an average-sized trunk.

A type of short-limbed dwarfism that is manifest beginning in the neonatal period.

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.

A deformity of the chest caused by overgrowth of the ribs and characterized by protrusion of the sternum.

Reduced width of the chest from side to side, associated with a reduced distance from the sternal notch to the tip of the shoulder.

Reduced rib length.

One or more abnormally short long bone.

Underdevelopment of the ilium ala.

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.

A horizontal (flat) conformation of the ribs, the long curved bones that form the rib cage and normally progressively oblique (slanted) from ribs 1 through 9, then less slanted through rib 12.

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

Tooth agenesis in some form is a common human anomaly that affects approximately 20% of the population. Although tooth agenesis is associated with numerous syndromes, several case reports describe nonsyndromic forms that are either sporadic or familial in nature, as reviewed by Gorlin et al. (1990). The incidence of familial tooth agenesis varies with each class of teeth. Most commonly affected are third molars (wisdom teeth), followed by either upper lateral incisors or lower second premolars; agenesis involving first and second molars is very rare. Also see 114600 and 302400. Selective tooth agenesis without associated systemic disorders has sometimes been divided into 2 types: oligodontia, defined as agenesis of 6 or more permanent teeth, and hypodontia, defined as agenesis of less than 6 teeth. The number in both cases does not include absence of third molars (wisdom teeth). Faulty use of the terms, however, have confounded their use. The term 'partial anodontia' is obsolete (Salinas, 1978). Genetic Heterogeneity of Selective Tooth Agenesis Other forms of selective tooth agenesis include STHAG2 (602639), mapped to chromosome 16q12; STHAG3 (604625), caused by mutation in the PAX9 gene (167416) on chromosome 14q12; STHAG4 (150400), caused by mutation in the WNT10A gene (606268) on chromosome 2q35; STHAG5 (610926), mapped to chromosome 10q11; STHAG7 (616724), caused by mutation in the LRP6 gene (603507) on chromosome 12p13; STHAG8 (617073), caused by mutation in the WNT10B gene (601906) on chromosome 12q13; STHAG9 (617275), caused by mutation in the GREM2 gene (608832) on chromosome 1q43; STHAG10 (620173), caused by mutation in the TSPEAR gene (612920) on chromosome 21q22; and STHAGX1 (313500), caused by mutation in the EDA gene (300451) on chromosome Xq13. A type of selective tooth agenesis that was formerly designated STHAG6 has been incorporated into the dental anomalies and short stature syndrome (DASS; 601216). Of 34 unrelated patients with nonsyndromic tooth agenesis, van den Boogaard et al. (2012) found that 56% (19 patients) had mutations in the WNT10A gene (STHAG4), whereas only 3% and 9% had mutations in the MSX1 (STHAG1) and PAX9 (STHAG3) genes, respectively. The authors concluded that WNT10A is a major gene in the etiology of isolated hypodontia. Genotype-Phenotype Correlations Yu et al. (2016) observed that the most frequently missing permanent teeth in WNT10B-associated oligodontia were the lateral incisors (83.3%), whereas premolars were missing only 51.4% of the time, which they noted was a pattern 'clearly different' from the oligodontia patterns resulting from WNT10A mutations. They also stated that the selective pattern in WNT10B mutants was different from that associated with mutations in other genes, such as MSX1, in which second premolars are missing, and PAX9, in which there is agenesis of molars.

A tooth present at birth or erupting within the first month of life.

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

Any abnormality of the alveolar ridges (on the upper or lower jaws). The alveolar ridges contain the sockets (alveoli) of the teeth.

Ectodermal dysplasia is a group of conditions in which there is abnormal development of the skin, hair, nails, teeth, or sweat glands.

The presence of developmental dysplasia of the nail.