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).

Abnormally long and slender fingers ("spider fingers").

A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced.

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.

Divergence of the longitudinal axis of the hand at the wrist in a posterior (ulnar) direction (i.e., towards the little finger).

Excessively deep creases of the palm.

An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.

A deficiency or slowing down of growth pre- and postnatally.

A tall and slim body build with increased arm span to height ratio (>1.05) and a reduced upper-to-lower segment ratio (<0.85), i.e., unusually long arms and legs. The extremities as well as the hands and feet are unusually slim.

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Feeding problem necessitating food and nutrient delivery via a tube.

Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions.

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.

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

The condition of inability to eat normally treated by placement of a thin tube through the nose into the stomach that is then used to carry food.

A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter.

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.

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).

Autism, the prototypic pervasive developmental disorder (PDD), is usually apparent by 3 years of age. It is characterized by a triad of limited or absent verbal communication, a lack of reciprocal social interaction or responsiveness, and restricted, stereotypic, and ritualized patterns of interests and behavior (Bailey et al., 1996; Risch et al., 1999). 'Autism spectrum disorder,' sometimes referred to as ASD, is a broader phenotype encompassing the less severe disorders Asperger syndrome (see ASPG1; 608638) and pervasive developmental disorder, not otherwise specified (PDD-NOS). 'Broad autism phenotype' includes individuals with some symptoms of autism, but who do not meet the full criteria for autism or other disorders. Mental retardation coexists in approximately two-thirds of individuals with ASD, except for Asperger syndrome, in which mental retardation is conspicuously absent (Jones et al., 2008). Genetic studies in autism often include family members with these less stringent diagnoses (Schellenberg et al., 2006). Levy et al. (2009) provided a general review of autism and autism spectrum disorder, including epidemiology, characteristics of the disorder, diagnosis, neurobiologic hypotheses for the etiology, genetics, and treatment options. Genetic Heterogeneity of Autism Autism is considered to be a complex multifactorial disorder involving many genes. Accordingly, several loci have been identified, some or all of which may contribute to the phenotype. Included in this entry is AUTS1, which has been mapped to chromosome 7q22. Other susceptibility loci include AUTS3 (608049), which maps to chromosome 13q14; AUTS4 (608636), which maps to chromosome 15q11; AUTS6 (609378), which maps to chromosome 17q11; AUTS7 (610676), which maps to chromosome 17q21; AUTS8 (607373), which maps to chromosome 3q25-q27; AUTS9 (611015), which maps to chromosome 7q31; AUTS10 (611016), which maps to chromosome 7q36; AUTS11 (610836), which maps to chromosome 1q41; AUTS12 (610838), which maps to chromosome 21p13-q11; AUTS13 (610908), which maps to chromosome 12q14; AUTS14A (611913), which has been found in patients with a deletion of a region of 16p11.2; AUTS14B (614671), which has been found in patients with a duplication of a region of 16p11.2; AUTS15 (612100), associated with mutation in the CNTNAP2 gene (604569) on chromosome 7q35-q36; AUTS16 (613410), associated with mutation in the SLC9A9 gene (608396) on chromosome 3q24; AUTS17 (613436), associated with mutation in the SHANK2 gene (603290) on chromosome 11q13; AUTS18 (615032), associated with mutation in the CHD8 gene (610528) on chromosome 14q11; AUTS19 (615091), associated with mutation in the EIF4E gene (133440) on chromosome 4q23; and AUTS20 (618830), associated with mutation in the NLGN1 gene (600568) on chromosome 3q26. (NOTE: the symbol 'AUTS2' has been used to refer to a gene on chromosome 7q11 (KIAA0442; 607270) and therefore is not used as a part of this autism locus series.) There are several X-linked forms of autism susceptibility: AUTSX1 (300425), associated with mutations in the NLGN3 gene (300336); AUTSX2 (300495), associated with mutations in NLGN4 (300427); AUTSX3 (300496), associated with mutations in MECP2 (300005); AUTSX4 (300830), associated with variation in the region on chromosome Xp22.11 containing the PTCHD1 gene (300828); AUTSX5 (300847), associated with mutations in the RPL10 gene (312173); and AUTSX6 (300872), associated with mutation in the TMLHE gene (300777). A locus on chromosome 2q (606053) associated with a phenotype including intellectual disability and speech deficits was formerly designated AUTS5. Folstein and Rosen-Sheidley (2001) reviewed the genetics of autism.

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.

Use of the same abnormal action in response to certain triggers or at random. They may be used as a way to regulate one's internal state but must otherwise have no apparent functional purpose.

Self-aggression.

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.

Underdevelopment of the corpus callosum.

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.

Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior.

A severe delay in the achievement of motor or mental milestones in the domains of development of a child.

Complete lack of development of speech and language abilities.

Underdevelopment of the inferior portion of the vermis of cerebellum.

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 type of repetitive behavior in which the affected individual repeatedly waves the hands and/or arms rhythmically.

Developmental hypoplasia of the mandible.

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.

An abnormality in which the mandible is mislocalised posteriorly.

The presence of an abnormal lateral curvature of the spine.

Scaphocephaly is a subtype of dolichocephaly where the anterior and posterior aspects of the cranial vault are pointed (boat-shaped). Scaphocephaly is caused by a precocious fusion of sagittal suture without other associated synostosis.

Wedge-shaped, or triangular head, with the apex of the triangle at the midline of the forehead and the base of the triangle at the occiput.

In newborns, the two frontal bones, two parietal bones, and one occipital bone are joined by fibrous sutures, which form a small posterior fontanelle, and a larger, diamond-shaped anterior fontanelle. These regions allow for the skull to pass the birth canal and for later growth. The fontanelles gradually ossify, whereby the posterior fontanelle usually closes by eight weeks and the anterior fontanelle by the 9th to 16th month of age. Large fontanelles are diagnosed if the fontanelles are larger than age-dependent norms.

Underdevelopment of the malar prominence of the jugal bone (zygomatic bone in mammals), appreciated in profile, frontal view, and/or by palpation.

Generalized muscular hypotonia (abnormally low muscle tone).

Premature fusion of the metopic suture.

Chronic loss of joint motion of the proximal interphalangeal joint of the 4th finger due to structural changes in non-bony tissue. That is, the PIP joint of a fourth finger is bent (flexed) and 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.

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

Laryngomalacia is a congenital abnormality of the laryngeal cartilage in which the cartilage is floppy and prolapses over the larynx during inspiration.

Increased susceptibility to infections.

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

Changes in alignment of teeth in the dental arch

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).

Hyperplasia of the gingiva (that is, a thickening of the soft tissue overlying the alveolar ridge. The degree of thickening ranges from involvement of the interdental papillae alone to gingival overgrowth covering the entire tooth crown.

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.

The palpebral fissure inclination is more than two standard deviations below the mean.

Increase in width of the nasal tip.

Abnormal narrowing of the choana (the posterior nasal aperture).

Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).

Thinned, deficient, or excessively arched ala nasi.

Posterior positioning of the nasal root in relation to the overall facial profile for age.

Forward prominence of the entire forehead, due to protrusion of the frontal bone.

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).

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

An abnormal configuration of the lower lip such that it is turned outward i.e., everted, with the Inner aspect of the lower lip vermilion (normally opposing the teeth) being visible in a frontal view.

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 from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.

Reduced distance from the anterior border of the naris to the subnasale.

Inclination of the anterior surface of the forehead from the vertical more than two standard deviations above the mean (objective); or apparently excessive posterior sloping of the forehead in a lateral view.

Height of the vermilion of the upper lip in the midline more than 2 SD below the mean. Alternatively, an apparently reduced height of the vermilion of the upper lip in the frontal view (subjective).

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

Decreased vertical distance from the vermilion border of the lower lip to the inferior-most point of the chin.

Decreased diameter of eyebrow hairs.

Increase in periorbital soft tissue.

Abnormally increased hair growth referring to a male pattern of body hair (androgenic hair).

Meeting of the medial eyebrows in the midline.

Mid upper eyelash length >10 mm or increased length of the eyelashes (subjective).

Reduced density of hairs.

A position of the fetus at delivery in which the fetus enters the birth canal with the buttocks or feet first.

Delivery of a fetus through surgical incisions made through the abdominal wall (laparotomy) and the uterine wall (hysterotomy).

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

The onset of secondary sexual characteristics before a normal age. Although it is difficult to define normal age ranges because of the marked variation with which puberty begins in normal children, precocious puberty can be defined as the onset of puberty before the age of 8 years in girls or 9 years in boys.

Presence of more than two nipples.

An eye that is protruding anterior to the plane of the face to a greater extent than is typical.

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

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).

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 eye that is more deeply recessed into the plane of the face than is typical.