—characterized by a round face, prominent nasal tip, polydactyly, and scoliosis.

—characterized by macrocephaly; small mandible; long, thin fingers; short, big toes; and anorectal and renal anomalies.

—typically involves malformations of the brain, heart, kidneys, and digits; usually lethal.

—hereditary (autosomal-recessive transmission); characterized by recurrent intrahepatic cholestasis, with lymphedema.

—X-linked recessive disorder characterized by short stature and musculoskeletal and genital anomalies of unknown etiology. Physical features include short stature (90%), hypertelorism, small nose with anteverted nares, broad philtrum and nasal bridge, abnormal auricles and widow’s peak, brachyclinodactyly (80%), broad feet with bulbous toes (75%), simian crease (70%), ptosis (50%), syndactyly (60%), “shawl” scrotum (80%), cryptorchidism (75%), inguinal hernia (60%), hyperopic astigmatism, large corneas, ophthalmoplegia, strabismus, delayed puberty, mild pectus excavatum, and prominent umbilicus. Radiographs show delayed bone age.

—recessive transmission; characterized by progressive cerebellar ataxia and pigmentary degeneration of the retina (starts with malabsorption of fat and progresses to ataxia); absent or reduced lipoproteins and
low carotene, vitamin A, and cholesterol levels; and acanthocytosis (spiny projections on red blood cells).

—characterized by hyperpigmented lichenoid plaques in the neck and axilla; may be associated with insulin resistance.

—autosomal-recessive transmission; characterized by zinc deficiency, vesicobullous and eczematous skin lesions in the perioral and perineal areas, cheeks, knees, and elbows; photophobia, conjunctivitis, and corneal dystrophy; chronic diarrhea; glossitis; nail dystrophy; growth retardation; and superinfections and Candida infections.

—characterized by a large pupil with little or no reaction to light; pupil may react to accommodation; and patients have hyperreflexia.

—cause unknown (rarely, X-linked recessive); absence of the major tracts connecting the right and left hemispheres is usually associated with hydrocephalus, seizures, developmental delay, abnormal head size, and hypertelorism.

—characterized by paucity or absence of intrahepatic bile ducts with progressive destruction of bile ducts; patients have a broad forehead, deep-set eyes that are widely spaced and underdeveloped, a small, pointed mandible, cardiac lesions, vertebral arch defects, and changes in the renal tubules and interstitium.

—most cases are autosomal dominant, a few are autosomal recessive; patients are prone to fractures and have mild anemia and craniofacial disproportion; radiologic changes include increased cortical bone density, longitudinal and transverse dense striations at the ends of the long bones, lucent and dense bands in the vertebrae, and thickening at the base of the skull.

—see McCune-Albright syndrome.

—unknown pathogenesis; characterized by megalencephaly in infants, dementia, spasticity, and ataxia; may cause seizures in younger children; patients become mute, immobile, and dependent; hyaline eosinophilic inclusions occur in the footplates of astrocytes in subpial and subependymal regions.

—several forms are hereditary male-to-male autosomal dominant, and an X-linked form also exists; characterized by neurosensory deafness and progressive renal failure.

—caused by a defect in the glycogen branching enzyme 1, 4-α-glucan branching enzyme; characterized by hepatomegaly and failure to thrive in the first few months, progressing to liver cirrhosis and splenomegaly.

—autosomal dominant; characterized by high and flat frontal bones, underdevelopment of the middle third of the face, hypertelorism and proptosis; a narrow, high, arched palate; a short, beaked nose; and syndactyly of the toes and digits.

—characterized by fixed contractures of the middle joints; present at birth.

—a developmental disorder on the higher functioning end of the autism spectrum. These patients, often viewed as brilliant, eccentric, and physically awkward, fail to develop relationships with peers, have repetitive and stereotyped behaviors, usually with hand movements (see www.asperger-syndrome. org).

—autosomal dominant; congenital aplasia of the skin; characterized by nail defects and recurrent blistering of the skin and mucous membranes.

—hypertrophy of the juxtaglomerular apparatus; characterized by hypokalemic alkalosis, hypochloremia, and hyperaldosteronism; patients have normal blood pressure but the renin level is elevated; may lead to mental retardation and small stature.

—characterized by hypoglycemia, macrosomia, and visceromegaly; patients have umbilical anomalies and renal medullary dysplasia.

—unknown cause; involves relapsing iridocyclitis and recurrent oral and genital ulcerations; 50% of patients have arthritis.

—stasis of small intestine, usually secondary to incomplete bowel obstruction or a problem of intestinal motility.

—characterized by mental retardation; a third of patients have seizures and ocular malformations.

—autosomal recessive; characterized by erythema and telangiectasia in a butterfly distribution, photosensitivity, and dwarfism.

—characterized by irregularity of the medial aspect of the tibial metaphysis adjacent to the epiphysis; bowing starts as angulation at the metaphysis.

—defective tryptophan absorption; characterized by bluish stains on the diapers, digestive disturbances, fever, and visual difficulties.

—repeat episode of typhus; caused by a Rickettsia infection.

—begins with necrotizing pneumonia secondary to viral infection (e.g., adenovirus, influenza, measles); tuberculosis; or inhalation of fumes, talcum powder, or zinc; and involves the obstruction of small bronchi and bronchioles by fibrous tissue.

—autosomal-recessive familial cholestasis; characterized by hepatomegaly, pruritus, splenomegaly, elevated bile acids, and gallstones.

—autosomal recessive; cystic dilation of the intrahepatic bile ducts; characterized by recurrent bouts of cholangitis and biliary abscesses secondary to bile stasis and gallstones.

—autosomal dominant; characterized by ocular coloboma, down-slanting eyes, congenital heart disease, and anal atresia.

—most common cause of chronic peripheral neuropathy; characterized by foot drop, high-arch foot; patients may have stocking-glove sensory loss.

—autosomal-recessive disorder; involves partial oculocutaneous albinism, increased susceptibility to infection, lack of natural killer
cells, and large lysosome-like granules in many tissues; patients have splenomegaly, hypersplenism, hepatomegaly, lymphadenopathy, nystagmus photophobia, and peripheral neuropathy.

—telangiectasia of retinal vessels, with subretinal exudate.

—intraspinous vascular anomaly and port-wine stains.

—autosomal recessive; characterized by dwarfism, mental retardation, bird-like facies, premature senility, and photosensitivity.

—prenatal growth retardation; characterized by microcephaly, hirsutism, anteverted nares, down-turned mouth, mental retardation, and congenital heart defects.

—characterized by growth retardation, mental deficiency, hypotonia, microcephaly, round “moon face,” hypertelorism, epicanthal folds, and down-slanting palpebral fissures.

—type 1 is recessive; a deficiency of uridine diphosphate glucuronyl transferase causes a rapid increase in the unconjugated bilirubin level on the first day of life; no hemolysis occurs and patients have no conjugation activity; type 2 is autosomal dominant and characterized by variable penetrance and partial activity of uridine diphosphate glucuronyl transferase.

—diffuse intestinal polyps involving large and small intestine; characterized by alopecia, brown skin lesions, and onychatrophia; patients have diarrhea and protein-losing enteropathy.

—autosomal dominant with a range of expressivity; characterized by exophthalmos, hypertelorism, and hypoplasia of maxilla; patients have oral cavity anomalies and premature closure of the external auditory meatus.

—syndrome involving lack of granulocyte macrophage colony-stimulating factor; characterized by fever, mouth lesions, cervical adenitis, and gastroenteritis occurring every 3 to 6 weeks; neutrophil count may be zero.

—fatal; infantile myopathy with renal dysfunction; involves abnormal mitochondria and lipid and glycogen accumulation; patient has weak cry, poor muscle tone, poor suck, and lactic acidosis.

—autosomal recessive; characterized by xeroderma pigmentosum with mental retardation, dwarfism, and hypogonadism; skin is unable to repair itself after exposure to ultraviolet light; patients may have erythema, scaling bullae, crusting telangiectasia keratoses, photophobia, corneal opacities, and tumors of the eyelids.

—failure of erythropoiesis; characterized by macrocytic anemia; patients have anemia, pallor, and weakness, no hepatomegaly, elevated fetal hemoglobin, and defect in abduction with retraction of the eye on adduction.

—thymic hypoplasia with hypocalcemia; patients have tetany, abnormal facies, congenital heart disease, and increased incidence of infection.