Wilson disease is a disorder of copper metabolism that, when untreated, can present with hepatic, neurologic, or psychiatric disturbances – or a combination of these – in individuals ages three years to older than 70 years. Manifestations in untreated individuals vary among and within families. Liver disease can include recurrent jaundice, simple acute self-limited hepatitis-like illness, autoimmune-type hepatitis, fulminant hepatic failure, or chronic liver disease. Neurologic presentations can include dysarthria, movement disorders (tremors, involuntary movements, chorea, choreoathetosis), dystonia (mask-like facies, rigidity, gait disturbance, pseudobulbar involvement), dysautonomia, seizures, sleep disorders, or insomnia. Psychiatric disturbances can include depression, bipolar disorder / bipolar spectrum disorder, neurotic behaviors, personality changes, or psychosis. Other multisystem involvement can include the eye (Kayser-Fleischer rings), hemolytic anemia, the kidneys, the endocrine glands, and the heart.

Single large-scale mitochondrial DNA deletion syndromes (SLSMDSs) comprise overlapping clinical phenotypes including Kearns-Sayre syndrome (KSS), KSS spectrum, Pearson syndrome (PS), chronic progressive external ophthalmoplegia (CPEO), and CPEO-plus. KSS is a progressive multisystem disorder with onset before age 20 years characterized by pigmentary retinopathy, CPEO, and cardiac conduction abnormality. Additional features can include cerebellar ataxia, tremor, intellectual disability or cognitive decline, dementia, sensorineural hearing loss, oropharyngeal and esophageal dysfunction, exercise intolerance, muscle weakness, and endocrinopathies. Brain imaging typically shows bilateral lesions in the globus pallidus and white matter. KSS spectrum includes individuals with KSS in addition to individuals with ptosis and/or ophthalmoparesis and at least one of the following: retinopathy, ataxia, cardiac conduction defects, hearing loss, growth deficiency, cognitive impairment, tremor, or cardiomyopathy. Compared to CPEO-plus, individuals with KSS spectrum have more severe muscle involvement (e.g., weakness, atrophy) and overall have a worse prognosis. PS is characterized by pancytopenia (typically transfusion-dependent sideroblastic anemia with variable cell line involvement), exocrine pancreatic dysfunction, poor weight gain, and lactic acidosis. PS manifestations also include renal tubular acidosis, short stature, and elevated liver enzymes. PS may be fatal in infancy due to neutropenia-related infection or refractory metabolic acidosis. CPEO is characterized by ptosis, ophthalmoplegia, oropharyngeal weakness, variable proximal limb weakness, and/or exercise intolerance. CPEO-plus includes CPEO with additional multisystemic involvement including neuropathy, diabetes mellitus, migraines, hypothyroidism, neuropsychiatric manifestations, and optic neuropathy. Rarely, an SLSMDS can manifest as Leigh syndrome, which is characterized as developmental delays, neurodevelopmental regression, lactic acidosis, and bilateral symmetric basal ganglia, brain stem, and/or midbrain lesions on MRI.

Autoimmune polyglandular syndrome type I (APS1) is characterized by the presence of 2 of 3 major clinical symptoms: Addison disease, and/or hypoparathyroidism, and/or chronic mucocutaneous candidiasis (Neufeld et al., 1981). However, variable APS1 phenotypes have been observed, even among sibs. In addition, some patients may exhibit apparent isolated hypoparathyroidism, an early manifestation of APS1 with peak incidence at around age 5 years; over long-term follow-up, the development of additional features of APS1 may be observed (Cranston et al., 2022).

Individuals with 22q11.2 deletion syndrome (22q11.2DS) can present with a wide range of features that are highly variable, even within families. The major clinical manifestations of 22q11.2DS include congenital heart disease, particularly conotruncal malformations (ventricular septal defect, tetralogy of Fallot, interrupted aortic arch, and truncus arteriosus), palatal abnormalities (velopharyngeal incompetence, submucosal cleft palate, bifid uvula, and cleft palate), immune deficiency, characteristic facial features, and learning difficulties. Hearing loss can be sensorineural and/or conductive. Laryngotracheoesophageal, gastrointestinal, ophthalmologic, central nervous system, skeletal, and genitourinary anomalies also occur. Psychiatric illness and autoimmune disorders are more common in individuals with 22q11.2DS.

The Murk Jansen type of metaphyseal chondrodysplasia is characterized by severe short stature, short bowed limbs, clinodactyly, prominent upper face, and small mandible. Hypercalcemia and hypophosphatemia occur despite the lack of parathyroid abnormalities (summary by Cohen, 2002).

CHD7 disorder encompasses the entire phenotypic spectrum of heterozygous CHD7 pathogenic variants that includes CHARGE syndrome as well as subsets of features that comprise the CHARGE syndrome phenotype. The mnemonic CHARGE syndrome, introduced in the premolecular era, stands for coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear anomalies (including deafness). Following the identification of the genetic cause of CHD7 disorder, the phenotypic spectrum expanded to include cranial nerve anomalies, vestibular defects, cleft lip and/or palate, hypothyroidism, tracheoesophageal anomalies, brain anomalies, seizures, and renal anomalies. Life expectancy highly depends on the severity of manifestations; mortality can be high in the first few years when severe birth defects (particularly complex heart defects) are present and often complicated by airway and feeding issues. In childhood, adolescence, and adulthood, decreased life expectancy is likely related to a combination of residual heart defects, infections, aspiration or choking, respiratory issues including obstructive and central apnea, and possibly seizures. Despite these complications, the life expectancy for many individuals can be normal.

Kabuki syndrome (KS) is characterized by typical facial features (long palpebral fissures with eversion of the lateral third of the lower eyelid; arched and broad eyebrows; short columella with depressed nasal tip; large, prominent, or cupped ears), minor skeletal anomalies, persistence of fetal fingertip pads, mild-to-moderate intellectual disability, and postnatal growth deficiency. Other findings may include: congenital heart defects, genitourinary anomalies, cleft lip and/or palate, gastrointestinal anomalies including anal atresia, ptosis and strabismus, and widely spaced teeth and hypodontia. Functional differences can include: increased susceptibility to infections and autoimmune disorders, seizures, endocrinologic abnormalities (including isolated premature thelarche in females), feeding problems, and hearing loss.

HDR syndrome (HDRS), also known as Barakat syndrome, is a heterogeneous disorder characterized by the triad of Hypoparathyroidism (H), nerve Deafness (D) and/or Renal disease (R). Variable clinical features include hypogonadotrophic hypogonadism, polycystic ovaries, congenital heart disease, retinitis pigmentosa, and cognitive disability (Barakat et al., 2018).

MPV17-related mitochondrial DNA (mtDNA) maintenance defect presents in the vast majority of affected individuals as an early-onset encephalohepatopathic (hepatocerebral) disease that is typically associated with mtDNA depletion, particularly in the liver. A later-onset neuromyopathic disease characterized by myopathy and neuropathy, and associated with multiple mtDNA deletions in muscle, has also rarely been described. MPV17-related mtDNA maintenance defect, encephalohepatopathic form is characterized by: Hepatic manifestations (liver dysfunction that typically progresses to liver failure, cholestasis, hepatomegaly, and steatosis); Neurologic involvement (developmental delay, hypotonia, microcephaly, and motor and sensory peripheral neuropathy); Gastrointestinal manifestations (gastrointestinal dysmotility, feeding difficulties, and failure to thrive); and Metabolic derangements (lactic acidosis and hypoglycemia). Less frequent manifestations include renal tubulopathy, nephrocalcinosis, and hypoparathyroidism. Progressive liver disease often leads to death in infancy or early childhood. Hepatocellular carcinoma has been reported.

A very rare ectodermal dysplasia syndrome, described in 2 adult brothers, characterized by the association of hypoparathyroidism, nephropathy, congenital lymphedema, mitral valve prolapse and brachytelephalangy. Additional features include mild facial dysmorphism, hypertrichosis and nail abnormalities.

A rare genetic developmental defect during embryogenesis disorder with characteristics of craniofacial dysmorphism (including brachycephaly, prominent forehead, sparse lateral eyebrows, severe hypertelorism, upslanting palpebral fissures, epicanthal folds, protruding ears, broad nasal bridge, pointed nasal tip, flat philtrum, anteverted nostrils, large mouth, thin upper vermilion border, highly arched palate and mild micrognathia) associated with osteopenia leading to repeated long bone fractures, severe myopia, mild to moderate sensorineural or mixed hearing loss, enamel hypoplasia, sloping shoulders and mild intellectual disability. There is evidence the disease can be caused by homozygous mutation in the IRX5 gene on chromosome 16q11.2.

FAM111A-related skeletal dysplasias include the milder phenotype of Kenny-Caffey syndrome (KCS) and a more severe lethal phenotype, osteocraniostenosis (OCS). KCS is characterized by proportionate short stature (typically postnatal onset), relative macrocephaly, large anterior fontanel with delayed closure, characteristic facial features, cortical thickening of the long bones with stenosis of the medullary cavity, and ophthalmologic and dental manifestations. OCS is characterized by intrauterine growth deficiency, microcephaly, characteristic facial features, decreased skull ossification, slender long bones with cortical thickening, stenosis of the medullary cavity of the long bones, flared metaphyses, and thin ribs with thoracic and pulmonary hypoplasia leading to respiratory insufficiency. Perinatal fractures may occur. Primary hypoparathyroidism with hypocalcemia and hyperphosphatemia can occur in individuals with KCS and OCS.

Alport syndrome is characterized by kidney manifestations, sensorineural hearing loss (SNHL), and ocular manifestations. In the absence of treatment, kidney disease progresses from microhematuria to proteinuria, progressive kidney insufficiency, and end-stage kidney disease (ESKD) in most males with X-linked Alport syndrome (XLAS), and in most males and females with autosomal recessive Alport syndrome (ARAS). Progressive SNHL is usually present by late childhood or early adolescence. Ocular findings include anterior lenticonus (which is virtually pathognomonic), maculopathy (whitish or yellowish flecks or granulations in the perimacular region), corneal endothelial vesicles (posterior polymorphous dystrophy), and recurrent corneal erosion. In females with XLAS and individuals with autosomal dominant Alport syndrome (ADAS), ESKD is frequently delayed until later adulthood, SNHL is relatively late in onset, and ocular involvement is rare.

Vertebral anomalies and variable endocrine and T-cell dysfunction is a syndrome characterized by an overlapping spectrum of features. Skeletal malformations primarily involve the vertebrae, and endocrine abnormalities involving parathyroid hormone (PTH; 168450), growth hormone (GH1; 139250), and the thyroid gland have been reported. T-cell abnormalities have been observed, with some patients showing thymus gland aplasia or hypoplasia. Patients have mild craniofacial dysmorphism, and some show developmental delay or behavioral problems. Cardiac defects may be present (Liu et al., 2018).

Garfield and Karaplis (2001) reviewed the various causes and clinical forms of hypoparathyroidism. They noted that hypoparathyroidism is a clinical disorder characterized by hypocalcemia and hyperphosphatemia. It manifests when parathyroid hormone (PTH; 168450) secreted from the parathyroid glands is insufficient to maintain normal extracellular fluid calcium concentrations or, less commonly, when PTH is unable to function optimally in target tissues, despite adequate circulating levels. Genetic Heterogeneity of Familial Isolated Hypoparathyroidism FIH2 (618883) is caused by mutation in the GCM2 gene (603716). An X-linked form of familial hypoparathyroidism, HYPX (307700), is caused by interstitial deletion/insertion on chromosome Xq27.1, which may have a position effect on expression of SOX3 (313430). Congenital absence of the parathyroid and thymus glands (III and IV pharyngeal pouch syndrome, or DiGeorge syndrome, 188400) is usually a sporadic condition (Taitz et al., 1966).