Kearns-Sayre syndrome- MedGen UID:
- 9618
- •Concept ID:
- C0022541
- •
- Disease or Syndrome
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.
Autosomal dominant optic atrophy classic form- MedGen UID:
- 137902
- •Concept ID:
- C0338508
- •
- Disease or Syndrome
Autosomal dominant optic atrophy is characterized by an insidious onset of visual impairment in early childhood with moderate to severe loss of visual acuity, temporal optic disc pallor, color vision deficits, and centrocecal scotoma of variable density (Votruba et al., 1998).
Some patients with mutations in the OPA1 gene may also develop extraocular neurologic features, such as deafness, progressive external ophthalmoplegia, muscle cramps, hyperreflexia, and ataxia; see 125250. There appears to be a wide range of intermediate phenotypes (Yu-Wai-Man et al., 2010).
Yu-Wai-Man et al. (2009) provided a detailed review of autosomal dominant optic atrophy and Leber hereditary optic neuropathy (LHON; 535000), with emphasis on the selective vulnerability of retinal ganglion cells to mitochondrial dysfunction in both disorders.
Genetic Heterogeneity of Optic Atrophy
Also see optic atrophy-2 (OPA2; 311050), mapped to chromosome Xp11.4-p11.21; OPA3 (165300), caused by mutation in the OPA3 gene (606580) on chromosome 19q13; OPA4 (605293), mapped to chromosome 18q12.2-q12.3; OPA5 (610708), caused by mutation in the DNM1L gene (603850) on chromosome 12p11; OPA6 (258500), mapped to chromosome 8q21-q22; OPA7 (612989), caused by mutation in the TMEM126A gene (612988) on chromosome 11q14; OPA8 (616648), mapped to chromosome 16q21-q22; OPA9 (616289), caused by mutation in the ACO2 gene (100850) on chromosome 22q13; OPA10 (616732), caused by mutation in the RTN4IP1 gene (610502) on chromosome 6q21; OPA11 (617302), caused by mutation in the YME1L1 gene (607472) on chromosome 10p12; OPA12 (618977), caused by mutation in the AFG3L2 gene (604581) on chromosome 18p11; OPA13 (165510), caused by mutation in the SSBP1 gene (600439) on chromosome 7q34; OPA14 (620550), caused by mutation in the MIEF1 gene (615497) on chromosome 22q13; OPA15 (620583), caused by mutation in the MCAT gene (614479) on chromosome 22q13; and OPA16 (620629), caused by mutation in the MECR gene (608205) on chromosome 1p35.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1- MedGen UID:
- 371919
- •Concept ID:
- C1834846
- •
- Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined before the molecular basis was known. POLG-related disorders can therefore be considered an overlapping spectrum of disease presenting from early childhood to late adulthood. The age of onset broadly correlates with the clinical phenotype. In individuals with early-onset disease (prior to age 12 years), liver involvement, feeding difficulties, seizures, hypotonia, and muscle weakness are the most common clinical features. This group has the worst prognosis. In the juvenile/adult-onset form (age 12-40 years), disease is typically characterized by peripheral neuropathy, ataxia, seizures, stroke-like episodes, and, in individuals with longer survival, progressive external ophthalmoplegia (PEO). This group generally has a better prognosis than the early-onset group. Late-onset disease (after age 40 years) is characterized by ptosis and PEO, with additional features such as peripheral neuropathy, ataxia, and muscle weakness. This group overall has the best prognosis.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3- MedGen UID:
- 373087
- •Concept ID:
- C1836439
- •
- Disease or Syndrome
Progressive external ophthalmoplegia is characterized by multiple mitochondrial DNA deletions in skeletal muscle. The most common clinical features include adult onset of weakness of the external eye muscles and exercise intolerance. Patients with C10ORF2-linked adPEO may have other clinical features including proximal muscle weakness, ataxia, peripheral neuropathy, cardiomyopathy, cataracts, depression, and endocrine abnormalities (summary by Fratter et al., 2010).
For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant progressive external ophthalmoplegia, see PEOA1 (157640).
PEO caused by mutations in the POLG gene (174763) is associated with more complicated phenotypes than PEO caused by mutations in the SLC25A4 (103220) or C10ORF2 genes (Lamantea et al., 2002).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 2- MedGen UID:
- 322925
- •Concept ID:
- C1836460
- •
- Disease or Syndrome
Progressive external ophthalmoplegia is characterized by multiple mitochondrial DNA deletions in skeletal muscle. The most common clinical features include adult onset of weakness of the external eye muscles and exercise intolerance. Both autosomal dominant and autosomal recessive inheritance can occur; autosomal recessive inheritance is usually more severe (Filosto et al., 2003; Luoma et al., 2004).
PEO caused by mutations in the POLG gene are associated with more complicated phenotypes than those forms caused by mutations in the ANT1 or C10ORF2 genes (Lamantea et al., 2002).
For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant progressive external ophthalmoplegia, see PEOA1 (157640).
Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis- MedGen UID:
- 375302
- •Concept ID:
- C1843851
- •
- Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined before the molecular basis was known. POLG-related disorders can therefore be considered an overlapping spectrum of disease presenting from early childhood to late adulthood. The age of onset broadly correlates with the clinical phenotype. In individuals with early-onset disease (prior to age 12 years), liver involvement, feeding difficulties, seizures, hypotonia, and muscle weakness are the most common clinical features. This group has the worst prognosis. In the juvenile/adult-onset form (age 12-40 years), disease is typically characterized by peripheral neuropathy, ataxia, seizures, stroke-like episodes, and, in individuals with longer survival, progressive external ophthalmoplegia (PEO). This group generally has a better prognosis than the early-onset group. Late-onset disease (after age 40 years) is characterized by ptosis and PEO, with additional features such as peripheral neuropathy, ataxia, and muscle weakness. This group overall has the best prognosis.
Ataxia, early-onset, with oculomotor apraxia and hypoalbuminemia- MedGen UID:
- 395301
- •Concept ID:
- C1859598
- •
- Disease or Syndrome
Ataxia-oculomotor apraxia syndrome is an early-onset autosomal recessive cerebellar ataxia with peripheral axonal neuropathy, oculomotor apraxia (defined as the limitation of ocular movements on command), and hypoalbuminemia (Moreira et al., 2001).
Genetic Heterogeneity of Ataxia-Oculomotor Apraxia
See also AOA2 (606002), caused by mutation in the SETX gene (608465) on chromosome 9q34; AOA3 (615217), caused by mutation in the PIK3R5 gene (611317) on chromosome 17p; and AOA4 (616267), caused by mutation in the PNKP gene (605610) on chromosome 19q13.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 4- MedGen UID:
- 350480
- •Concept ID:
- C1864668
- •
- Disease or Syndrome
Progressive external ophthalmoplegia-4 (PEOA4) is an autosomal dominant form of mitochondrial disease that variably affects skeletal muscle, the nervous system, the liver, and the gastrointestinal tract. Age at onset ranges from infancy to adulthood. The phenotype ranges from relatively mild, with adult-onset skeletal muscle weakness and weakness of the external eye muscles, to severe, with a multisystem disorder characterized by delayed psychomotor development, lactic acidosis, constipation, and liver involvement (summary by Young et al., 2011).
For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant progressive external ophthalmoplegia, see PEOA1 (157640).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 5- MedGen UID:
- 413981
- •Concept ID:
- C2751319
- •
- Disease or Syndrome
Four phenotypes comprise the RRM2B mitochondrial DNA maintenance defects (RRM2B-MDMDs): RRM2B encephalomyopathic MDMD, the most severe phenotype, usually manifesting shortly after birth as hypotonia, poor feeding, and faltering growth requiring hospitalization. Subsequent assessments are likely to reveal multisystem involvement including sensorineural hearing loss, renal tubulopathy, and respiratory failure. Autosomal dominant progressive external ophthalmoplegia (adPEO), typically adult onset; other manifestations can include ptosis, bulbar dysfunction, fatigue, and muscle weakness. RRM2B autosomal recessive progressive external ophthalmoplegia (arPEO), a typically childhood-onset predominantly myopathic phenotype of PEO, ptosis, proximal muscle weakness, and bulbar dysfunction. RRM2B mitochondrial neurogastrointestinal encephalopathy (MNGIE)-like, characterized by progressive ptosis, ophthalmoplegia, gastrointestinal dysmotility, cachexia, and peripheral neuropathy. To date, 78 individuals from 52 families with a molecularly confirmed RRM2B-MDMD have been reported.
Mitochondrial DNA depletion syndrome 4b- MedGen UID:
- 462264
- •Concept ID:
- C3150914
- •
- Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined before the molecular basis was known. POLG-related disorders can therefore be considered an overlapping spectrum of disease presenting from early childhood to late adulthood. The age of onset broadly correlates with the clinical phenotype. In individuals with early-onset disease (prior to age 12 years), liver involvement, feeding difficulties, seizures, hypotonia, and muscle weakness are the most common clinical features. This group has the worst prognosis. In the juvenile/adult-onset form (age 12-40 years), disease is typically characterized by peripheral neuropathy, ataxia, seizures, stroke-like episodes, and, in individuals with longer survival, progressive external ophthalmoplegia (PEO). This group generally has a better prognosis than the early-onset group. Late-onset disease (after age 40 years) is characterized by ptosis and PEO, with additional features such as peripheral neuropathy, ataxia, and muscle weakness. This group overall has the best prognosis.
Mitochondrial DNA depletion syndrome 11- MedGen UID:
- 767376
- •Concept ID:
- C3554462
- •
- Disease or Syndrome
Mitochondrial DNA depletion syndrome-11 is an autosomal recessive mitochondrial disorder characterized by onset in childhood or adulthood of progressive external ophthalmoplegia (PEO), muscle weakness and atrophy, exercise intolerance, and respiratory insufficiency due to muscle weakness. More variable features include spinal deformity, emaciation, and cardiac abnormalities. Skeletal muscle biopsies show deletion and depletion of mitochondrial DNA (mtDNA) with variable defects in respiratory chain enzyme activities (summary by Kornblum et al., 2013).
For a discussion of genetic heterogeneity of autosomal recessive mtDNA depletion syndromes, see MTDPS1 (603041).
Mitochondrial DNA deletion syndrome with progressive myopathy- MedGen UID:
- 767513
- •Concept ID:
- C3554599
- •
- Disease or Syndrome
Autosomal dominant progressive external ophthalmoplegia-6 (PEOA6) is characterized by muscle weakness, mainly affecting the lower limbs, external ophthalmoplegia, exercise intolerance, and mitochondrial DNA (mtDNA) deletions on muscle biopsy. Symptoms may appear in childhood or adulthood and show slow progression (summary by Ronchi et al., 2013).
For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant progressive external ophthalmoplegia, see PEOA1 (157640).
Combined oxidative phosphorylation defect type 20- MedGen UID:
- 863097
- •Concept ID:
- C4014660
- •
- Disease or Syndrome
Combined oxidative phosphorylation defect type 20 is a rare mitochondrial oxidative phosphorylation disorder characterized by variable combination of psychomotor delay, hypotonia, muscle weakness, seizures, microcephaly, cardiomyopathy and mild dysmorphic facial features. Variable types of structural brain anomalies have also been reported. Biochemical studies typically show decreased activity of mitochondrial complexes (mainly complex I).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1- MedGen UID:
- 897191
- •Concept ID:
- C4225153
- •
- Disease or Syndrome
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined before the molecular basis was known. POLG-related disorders can therefore be considered an overlapping spectrum of disease presenting from early childhood to late adulthood. The age of onset broadly correlates with the clinical phenotype. In individuals with early-onset disease (prior to age 12 years), liver involvement, feeding difficulties, seizures, hypotonia, and muscle weakness are the most common clinical features. This group has the worst prognosis. In the juvenile/adult-onset form (age 12-40 years), disease is typically characterized by peripheral neuropathy, ataxia, seizures, stroke-like episodes, and, in individuals with longer survival, progressive external ophthalmoplegia (PEO). This group generally has a better prognosis than the early-onset group. Late-onset disease (after age 40 years) is characterized by ptosis and PEO, with additional features such as peripheral neuropathy, ataxia, and muscle weakness. This group overall has the best prognosis.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 2- MedGen UID:
- 901897
- •Concept ID:
- C4225312
- •
- Disease or Syndrome
Autosomal recessive progressive external ophthalmoplegia with mitochondrial DNA deletions-2 (PEOB2) is a mitochondrial disorder characterized by adult onset of progressive external ophthalmoplegia, exercise intolerance, muscle weakness, and signs and symptoms of spinocerebellar ataxia, such as impaired gait and dysarthria. Some patients may have respiratory insufficiency. Laboratory studies are consistent with a defect in mtDNA replication (summary by Reyes et al., 2015).
For a discussion of genetic heterogeneity of autosomal recessive PEO, see PEOB1 (258450).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 4- MedGen UID:
- 934700
- •Concept ID:
- C4310733
- •
- Disease or Syndrome
Autosomal recessive progressive external ophthalmoplegia with mitochondrial DNA deletions-4 (PEOB4) is characterized by adult onset of eye muscle weakness and proximal limb muscle weakness associated with deletions of mtDNA on skeletal muscle biopsy, which results from defective mtDNA replication in post-mitotic muscle tissue. Additional features are more variable (summary by Ronchi et al., 2012).
For a discussion of genetic heterogeneity of autosomal recessive PEO, see PEOB1 (258450).
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 3- MedGen UID:
- 934701
- •Concept ID:
- C4310734
- •
- Disease or Syndrome
Any autosomal recessive progressive external ophthalmoplegia in which the cause of the disease is a mutation in the TK2 gene.
Combined oxidative phosphorylation deficiency 33- MedGen UID:
- 1623699
- •Concept ID:
- C4540209
- •
- Disease or Syndrome
COXPD33 is an autosomal recessive multisystem disorder resulting from a defect in mitochondrial energy metabolism. The phenotype is highly variable, ranging from death in infancy to adult-onset progressive external ophthalmoplegia (PEO) and myopathy. A common finding is cardiomyopathy and increased serum lactate (summary by Feichtinger et al., 2017).
For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Mitochondrial DNA depletion syndrome 1- MedGen UID:
- 1631838
- •Concept ID:
- C4551995
- •
- Disease or Syndrome
Mitochondrial neurogastrointestinal encephalopathy (MNGIE) disease is characterized by progressive gastrointestinal dysmotility (manifesting as early satiety, nausea, dysphagia, gastroesophageal reflux, postprandial emesis, episodic abdominal pain and/or distention, and diarrhea); cachexia; ptosis/ophthalmoplegia or ophthalmoparesis; leukoencephalopathy; and demyelinating peripheral neuropathy (manifesting as paresthesias (tingling, numbness, and pain) and symmetric and distal weakness more prominently affecting the lower extremities). The order in which manifestations appear is unpredictable. Onset is usually between the first and fifth decades; in about 60% of individuals, symptoms begin before age 20 years.
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 5- MedGen UID:
- 1648331
- •Concept ID:
- C4748184
- •
- Disease or Syndrome
Combined oxidative phosphorylation deficiency 55- MedGen UID:
- 1806598
- •Concept ID:
- C5676915
- •
- Disease or Syndrome
Combined oxidative phosphorylation deficiency-55 (COXPD55) is characterized by global developmental delay, hypotonia, short stature, and impaired intellectual development with speech disabilities in childhood. Indolent progressive external ophthalmoplegia phenotype has been described in 1 patient (summary by Olahova et al., 2021).
For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Combined oxidative phosphorylation deficiency 56- MedGen UID:
- 1824034
- •Concept ID:
- C5774261
- •
- Disease or Syndrome
Combined oxidative phosphorylation deficiency-56 (COXPD56) is an autosomal recessive disorder characterized by lethargy at birth, hypotonia, developmental delay, myopathy, and ptosis (Thompson et al., 2022).
For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).