Wilson disease is a disorder of copper metabolism that can present with hepatic, neurologic, or psychiatric disturbances, or a combination of these, in individuals ranging from age three years to older than 50 years; symptoms vary among and within families. Liver disease includes recurrent jaundice, simple acute self-limited hepatitis-like illness, autoimmune-type hepatitis, fulminant hepatic failure, or chronic liver disease. Neurologic presentations include movement disorders (tremors, poor coordination, loss of fine-motor control, chorea, choreoathetosis) or rigid dystonia (mask-like facies, rigidity, gait disturbance, pseudobulbar involvement). Psychiatric disturbance includes depression, neurotic behaviors, disorganization of personality, and, occasionally, intellectual deterioration. Kayser-Fleischer rings, frequently present, result from copper deposition in Descemet's membrane of the cornea and reflect a high degree of copper storage in the body.

Lowe syndrome (oculocerebrorenal syndrome) is characterized by involvement of the eyes, central nervous system, and kidneys. Dense congenital cataracts are found in all affected boys and infantile glaucoma in approximately 50%. All boys have impaired vision; corrected acuity is rarely better than 20/100. Generalized hypotonia is noted at birth and is of central (brain) origin. Deep tendon reflexes are usually absent. Hypotonia may slowly improve with age, but normal motor tone and strength are never achieved. Motor milestones are delayed. Almost all affected males have some degree of intellectual disability; 10%-25% function in the low-normal or borderline range, approximately 25% in the mild-to-moderate range, and 50%-65% in the severe-to-profound range of intellectual disability. Affected males have varying degrees of proximal renal tubular dysfunction of the Fanconi type, including low molecular-weight (LMW) proteinuria, aminoaciduria, bicarbonate wasting and renal tubular acidosis, phosphaturia with hypophosphatemia and renal rickets, hypercalciuria, sodium and potassium wasting, and polyuria. The features of symptomatic Fanconi syndrome do not usually become manifest until after the first few months of life, except for LMW proteinuria. Glomerulosclerosis associated with chronic tubular injury usually results in slowly progressive chronic renal failure and end-stage renal disease between the second and fourth decades of life.

Hypophosphatasia is characterized by defective mineralization of growing or remodeling bone, with or without root-intact tooth loss, in the presence of low activity of serum and bone alkaline phosphatase. Clinical features range from stillbirth without mineralized bone at the severe end to pathologic fractures of the lower extremities in later adulthood at the mild end. While the disease spectrum is a continuum, seven clinical forms of hypophosphatasia are usually recognized based on age at diagnosis and severity of features: Perinatal (severe): characterized by pulmonary insufficiency and hypercalcemia. Perinatal (benign): prenatal skeletal manifestations that slowly resolve into one of the milder forms. Infantile: onset between birth and age six months of clinical features of rickets without elevated serum alkaline phosphatase activity. Severe childhood (juvenile): variable presenting features progressing to rickets. Mild childhood: low bone mineral density for age, increased risk of fracture, and premature loss of primary teeth with intact roots. Adult: characterized by stress fractures and pseudofractures of the lower extremities in middle age, sometimes associated with early loss of adult dentition. Odontohypophosphatasia: characterized by premature exfoliation of primary teeth and/or severe dental caries without skeletal manifestations.

A type of renal tubular acidosis characterized by a failure of the proximal tubular cells to reabsorb bicarbonate, leading to urinary bicarbonate wasting and subsequent acidemia.

Autosomal dominant hypophosphatemic rickets (ADHR) is characterized by isolated renal phosphate wasting, hypophosphatemia, and inappropriately normal 1,25-dihydroxyvitamin D3 (calcitriol) levels. Patients frequently present with bone pain, rickets, and tooth abscesses. In contrast to X-linked dominant hypophosphatemic rickets (XLH; 307800), ADHR shows incomplete penetrance, variable age at onset (childhood to adult), and resolution of the phosphate-wasting defect in rare cases (Econs et al., 1997). See also hypophosphatemic bone disease (146350). Genetic Heterogeneity of Hypophosphatemic Rickets Other forms of hypophosphatemic rickets include autosomal recessive forms, i.e., ARHR1 (241520), caused by mutation in the DMP1 gene (600980) on chromosome 4q21, and ARHR2 (613312), caused by mutation in the ENPP1 gene (173335) on chromosome 6q23. An X-linked dominant form (XLHR; 307800) is caused by mutation in the PHEX gene (300550), and an X-linked recessive form (300554) is caused by mutation in the CLCN5 gene (300008). Clinical Variability of Hypophosphatemic Rickets Hypophosphatemic rickets can be caused by disorders of vitamin D metabolism or action (see VDDR1A, 264700). A form of hypophosphatemic rickets with hypercalciuria (HHRH; 241530) is caused by mutation in the SLC34A3 gene (609826), and there is evidence that a form of hypophosphatemic rickets with hyperparathyroidism (612089) may be caused by a translocation that results in an increase in alpha-klotho levels (KLOTHO; 604824).

The phenotypic spectrum of X-linked hypophosphatemia (XLH) ranges from isolated hypophosphatemia to severe lower-extremity bowing. XLH frequently manifests in the first two years of life when lower-extremity bowing becomes evident with the onset of weight bearing; however, it sometimes is not manifest until adulthood, as previously unevaluated short stature. In adults, enthesopathy (calcification of the tendons, ligaments, and joint capsules) associated with joint pain and impaired mobility may be the initial presenting complaint. Persons with XLH are prone to spontaneous dental abscesses; sensorineural hearing loss has also been reported.

Any familial hypocalciuric hypercalcemia in which the cause of the disease is a mutation in the AP2S1 gene.

X-linked recessive hypophosphatemic rickets is a form of X-linked hypercalciuric nephrolithiasis, which comprises a group of disorders characterized by proximal renal tubular reabsorptive failure, hypercalciuria, nephrocalcinosis, and renal insufficiency. These disorders have also been referred to as the 'Dent disease complex' (Scheinman, 1998; Gambaro et al., 2004). For a general discussion of Dent disease, see 300009.

Dent disease, an X-linked disorder of proximal renal tubular dysfunction, is characterized by low molecular weight (LMW) proteinuria, hypercalciuria, and at least one additional finding including nephrocalcinosis, nephrolithiasis, hematuria, hypophosphatemia, chronic kidney disease (CKD), and evidence of X-linked inheritance. Males younger than age ten years may manifest only LMW proteinuria and/or hypercalciuria, which are usually asymptomatic. Thirty to 80% of affected males develop end-stage renal disease (ESRD) between ages 30 and 50 years; in some instances ESRD does not develop until the sixth decade of life or later. The disease may also be accompanied by rickets or osteomalacia, growth restriction, and short stature. Disease severity can vary within the same family. Males with Dent disease 2 (caused by pathogenic variants in OCRL) may also have mild intellectual disability, cataracts, and/or elevated muscle enzymes. Due to random X-chromosome inactivation, some female carriers may manifest hypercalciuria and, rarely, renal calculi and moderate LMW proteinuria. Females rarely develop CKD.

Any Fanconi syndrome in which the cause of the disease is a mutation in the SLC34A1 gene.

Fanconi-Bickel syndrome is a rare but well-defined clinical entity, inherited in an autosomal recessive mode and characterized by hepatorenal glycogen accumulation, proximal renal tubular dysfunction, and impaired utilization of glucose and galactose (Manz et al., 1987). Because no underlying enzymatic defect in carbohydrate metabolism had been identified and because metabolism of both glucose and galactose is impaired, a primary defect of monosaccharide transport across the membranes had been suggested (Berry et al., 1995; Fellers et al., 1967; Manz et al., 1987; Odievre, 1966). Use of the term glycogenosis type XI introduced by Hug (1987) is to be discouraged because glycogen accumulation is not due to the proposed functional defect of phosphoglucomutase, an essential enzyme in the common degradative pathways of both glycogen and galactose, but is secondary to nonfunctional glucose transport.

Immunodeficiency-82 with systemic inflammation (IMD82) is a complex autosomal dominant immunologic disorder characterized by recurrent infections with various organisms, as well as noninfectious inflammation manifest as lymphocytic organ infiltration with gastritis, colitis, and lung, liver, CNS, or skin disease. One of the more common features is inflammation of the stomach and bowel. Most patients develop symptoms in infancy or early childhood; the severity is variable. There may be accompanying fever, elevated white blood cell count, decreased B cells, hypogammaglobulinemia, increased C-reactive protein (CRP; 123260), and a generalized hyperinflammatory state. Immunologic workup shows variable B- and T-cell abnormalities such as skewed subgroups. Patients have a propensity for the development of lymphoma, usually in adulthood. At the molecular level, the disorder results from a gain-of-function mutation that leads to constitutive and enhanced activation of the intracellular inflammatory signaling pathway. Treatment with SYK inhibitors rescued human cell abnormalities and resulted in clinical improvement in mice (Wang et al., 2021).

Individuals with hereditary distal renal tubular acidosis (dRTA) typically present in infancy with failure to thrive, although later presentations can occur, especially in individuals with autosomal dominant SLC4A1-dRTA. Initial clinical manifestations can also include emesis, polyuria, polydipsia, constipation, diarrhea, decreased appetite, and episodes of dehydration. Electrolyte manifestations include hyperchloremic non-anion gap metabolic acidosis and hypokalemia. Renal complications of dRTA include nephrocalcinosis, nephrolithiasis, medullary cysts, and impaired renal function. Additional manifestations include bone demineralization (rickets, osteomalacia), growth deficiency, sensorineural hearing loss (in ATP6V0A4-, ATP6V1B1-, and FOXI1-dRTA), and hereditary hemolytic anemia (in some individuals with SLC4A1-dRTA).