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

Vesicoureteral reflux (VUR) is characterized by the reflux of urine from the bladder into the ureters and sometimes into the kidneys. It is a risk factor for urinary tract infections. Primary VUR results from a developmental defect of the ureterovesical junction (UVJ). In combination with intrarenal reflux, the resulting inflammatory reaction may result in renal injury or scarring, also called reflux nephropathy (RN). Extensive renal scarring impairs renal function and may predispose patients to hypertension, proteinuria, and renal insufficiency (summary by Lu et al., 2007). Genetic Heterogeneity of Vesicoureteral Reflux A locus designated VUR1 maps to chromosome 1p13. VUR2 (610878) is caused by mutation in the ROBO2 gene (602431) on chromosome 3p12; VUR3 (613674) is caused by mutation in the SOX17 gene (610928) on chromosome 8q11; VUR4 (614317) maps to chromosome 5; VUR5 (614318) maps to chromosome 13; VUR6 (614319) maps to chromosome 18; VUR7 (615390) maps to chromosome 12; and VUR8 (615963) is caused by mutation in the TNXB gene (600985) on chromosome 6p21. A possible X-linked form has been reported (VURX; 314550).

A connection of the right and left kidney by an isthmus of functioning renal parenchyma or fibrous tissue that crosses the midline.

An abnormality of the normal developmental rotation of the kidney leading to an abnormal orientation of the kidney.

Hypoplasia of the kidney.

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

A developmental anomaly in which the kidneys are fused and localized on the same side of the midline. This anomaly is thought to result from disruption of the normal embryologic migration of the kidneys.

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.

Webbing or fusion of the fingers or toes, involving soft parts only or including bone structure. Bony fusions are referred to as "bony" syndactyly if the fusion occurs in a radio-ulnar axis. Fusions of bones of the fingers or toes in a proximo-distal axis are referred to as "symphalangism".

A thumb with three phalanges in a single, proximo-distal axis. Thus, this term applies if the thumb has an accessory phalanx, leading to a digit like appearance of the thumb.

A form of polydactyly in which the extra digit or digits are localized on the side of the thumb or great toe.

Hypoplasia (congenital reduction in size) of the thumb.

An abnormal position of the hand in which the wrist is bent toward the radius (i.e., toward the thumb).

Underdevelopment of the radius.

Missing radius bone associated with congenital failure of development.

Underdevelopment of the humerus.

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

Developmental defect associated with absence of one or more metacarpal bones.

Underdevelopment of the thenar eminence with reduced palmar soft tissue mass surrounding the base of the thumb.

Underdevelopment of the ulna.

Absent thumb, i.e., the absence of both phalanges of a thumb and the associated soft tissues.

Abnormal outpouching or sac-like dilatation in the wall of an atery, vein or the heart.

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.

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

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).

Abnormal narrowing of the anal opening.

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

A type of stenosis of the external auditory meatus in which the opening of the external auditory meatus appears as a vertical slit.

The closed form of spina bifida with incomplete closure of a vertebral body with intact overlying skin.

The presence of an abnormal lateral curvature of the spine.

A displacement or misalignment of the humerus with respect to the other bones of the should joint. Note that a subluxation is a partial dislocation.

Facial nerve palsy is a dysfunction of cranial nerve VII (the facial nerve) that results in inability to control facial muscles on the affected side with weakness of the muscles of facial expression and eye closure. This can either be present in unilateral or bilateral form.

Underdevelopment of the pectoral muscle.

Underdevelopment of muscles of the arm.

A congenital anomaly characterized by a joining (fusion) of two or more cervical vertebral bodies with one another.

A structural anomaly of the nasopharynx.

Absence or abnormal closure of the choana (the posterior nasal aperture). Most embryologists believe that posterior choanal atresia results from a failure of rupture between the 35th and 38th day of fetal life of the partition which separates the bucconasal or buccopharyngeal membranes. The resultant choanal atresia may be unilateral or bilateral, bony or membranous, complete or incomplete. In over 90 per cent of cases the obstruction is bony, while in the remainder it is membranous. The bony type of atresia is commonly located 1-2 mm. anterior to the posterior edge of the hard palate, and the osseous septum varies in thickness from 1 to 10 mm. In the membranous form of choanal atresia the obstruction usually occurs further posteriorly. In approximately one third of cases the atresia is bilateral.

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).

An abnormal difference between the left and right sides of the face.

Duane syndrome is a strabismus condition clinically characterized by congenital non-progressive limited horizontal eye movement accompanied by globe retraction which results in narrowing of the palpebral fissure. The lateral movement anomaly results from failure of the abducens nucleus and nerve (cranial nerve VI) to fully innervate the lateral rectus muscle; globe retraction occurs as a result of abnormal innervation of the lateral rectus muscle by the oculomotor nerve (cranial nerve III). At birth, affected infants have restricted ability to move the affected eye(s) outward (abduction) and/or inward (adduction), though the limitations may not be recognized in early infancy. In addition, the globe retracts into the orbit with attempted adduction, accompanied by narrowing of the palpebral fissure. Many individuals with Duane syndrome have strabismus in primary gaze but can use a compensatory head turn to align the eyes, and thus can preserve binocular vision and avoid diplopia. Individuals with Duane syndrome who lack binocular vision are at risk for amblyopia. The majority of affected individuals with Duane syndrome have isolated Duane syndrome (i.e., they do not have other detected congenital anomalies). Other individuals with Duane syndrome fall into well-defined syndromic diagnoses. However, many individuals with Duane syndrome have non-ocular findings that do not fit a known syndrome; these individuals are included as part of the discussion of nonsyndromic Duane syndrome.

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.

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.

A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule.

A coloboma of the iris.

Reduced ability to turn the eyes inward in order to focus on a nearby object.

Underdevelopment of the optic disc, that is of the optic nerve head, where ganglion cell axons exit the eye to form the optic nerve.

An impaired ability of the eye to move in the outward direction (towards the side of the head).

Reduced ability to move the eye in the direction of the nose.

A notch or cleft of the retina.