Failure to thrive, and Dysarthria

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Microcephaly

SOURCES: ORPHANET OMIM MENDELIAN

Combined oxidative phosphorylation defect type 7 is a rare mitochondrial disease due to a defect in mitochondrial protein synthesis characterized by a variable phenotype that includes onset in infancy or early childhood of failure to thrive and psychomotor regression (after initial normal development), as well as ocular manifestations (such as ptosis, nystagmus, optic atrophy, ophthalmoplegia and reduced vision). Additional manifestations include bulbar paresis with facial weakness, hypotonia, difficulty chewing, dysphagia, mild dysarthria, ataxia, global muscle atrophy, and areflexia. It has a relatively slow disease progression with patients often living into the third decade of life.

COMBINED OXIDATIVE PHOSPHORYLATION DEFECT TYPE 7 Is also known as severe c12orf65-related combined oxidative phosphorylation defect|severe c12orf65-related coxpd|coxpd7

• Global developmental delay
• Generalized hypotonia
• Ataxia
• Nystagmus
• Failure to thrive

SOURCES: OMIM ORPHANET MENDELIAN

Classic galactosemia is a life-threatening metabolic disease with onset in the neonatal period. Infants usually develop feeding difficulties, lethargy, and severe liver disease.

CLASSIC GALACTOSEMIA Is also known as galt deficiency|galactose-1-phosphate uridyltransferase deficiency|galactosemia type 1

• Intellectual disability
• Ataxia
• Failure to thrive
• Cataract
• Feeding difficulties

SOURCES: ORPHANET MENDELIAN

Spinocerebellar ataxia-7 (SCA7) is an autosomal dominant neurodegenerative disorder characterized by adult onset of progressive cerebellar ataxia associated with pigmental macular dystrophy. In her classification of ataxia, Harding (1982) referred to progressive cerebellar ataxia with pigmentary macular degeneration as type II ADCA (autosomal dominant cerebellar ataxia). The age at onset, degree of severity, and rate of progression vary among and within families. Associated neurologic signs, such as ophthalmoplegia, pyramidal or extrapyramidal signs, deep sensory loss, or dementia, are also variable. Genetic anticipation is observed and is greater in paternal than in maternal transmissions (Benomar et al., 1994; summary by David et al., 1996).For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (OMIM ).

SPINOCEREBELLAR ATAXIA 7; SCA7 Is also known as opca iii|opca with macular degeneration and external ophthalmoplegia|adca, type ii|olivopontocerebellar atrophy iii|opca3|opca with retinal degeneration|autosomal dominant cerebellar ataxia, type ii

• Global developmental delay
• Generalized hypotonia
• Ataxia
• Nystagmus
• Failure to thrive

SOURCES: OMIM MENDELIAN

Mitochondrial complex III deficiency, nuclear type 8, is an autosomal recessive disorder characterized by progressive neurodegeneration with onset in childhood. Affected individuals may have normal or delayed early development, and often have episodic acute neurologic decompensation and regression associated with febrile illnesses. The developmental regression results in variable intellectual disability and motor deficits, such as hypotonia, axial hypertonia, and spasticity; some patients may lose the ability to walk independently. Laboratory studies show increased serum lactate and isolated deficiency of mitochondrial complex III in skeletal muscle and fibroblasts. Brain imaging shows a characteristic pattern of multifocal small cystic lesions in the periventricular and deep cerebral white matter (summary by Dallabona et al., 2016).For a discussion of genetic heterogeneity of mitochondrial complex III deficiency, see MC3DN1 (OMIM ).

• Intellectual disability
• Global developmental delay
• Generalized hypotonia
• Ataxia
• Nystagmus

SOURCES: OMIM MENDELIAN

CONDBA is a severe progressive neurodegenerative disorder characterized by loss of motor and cognitive skills between ages 2 and 7 years. Affected individuals may have normal development or mild developmental delay, but all eventually lose all motor skills, resulting in inability to walk, absence of language, and profound intellectual disability. Brain imaging shows progressive cerebral and cerebellar atrophy (summary by Edvardson et al., 2017).

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Ataxia

SOURCES: ORPHANET OMIM MENDELIAN

Spinocerebellar ataxia type 7 (SCA7), currently the only known form of autosomal dominant cerebellar ataxia type 2 (ADCA2; see this term), is a neurodegenerative disorder characterized by progressive ataxia, motor system abnormalities, dysarthria, dysphagia and retinal degeneration leading to progressive blindness.

SPINOCEREBELLAR ATAXIA TYPE 7 Is also known as ataxia with pigmentary retinopathy|sca7|cerebellar syndrome-pigmentary maculopathy syndrome

• Global developmental delay
• Ataxia
• Nystagmus
• Failure to thrive
• Muscle weakness

SOURCES: ORPHANET MENDELIAN

Mitochondrial DNA depletion syndrome-8A is a severe autosomal recessive disorder characterized by neonatal hypotonia, lactic acidosis, and neurologic deterioration. Renal tubular involvement may also occur (Bourdon et al., 2007).Mitochondrial DNA depletion syndrome-8B is characterized by ophthalmoplegia, ptosis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and brain MRI changes, known as the MNGIE phenotype (Shaibani et al., 2009).For a discussion of genetic heterogeneity of mtDNA depletion syndromes, see MTDPS1 (OMIM ).

MITOCHONDRIAL DNA DEPLETION SYNDROME, ENCEPHALOMYOPATHIC FORM WITH RENAL TUBULOPATHY Is also known as mitochondrial dna depletion syndrome, encephalomyopathic, with renal tubulopathy, autosomal recessive|mtdna depletion syndrome, encephalomyopathic form with renal tubulopathy

• Intellectual disability
• Seizures
• Generalized hypotonia
• Hearing impairment
• Failure to thrive

SOURCES: ORPHANET OMIM MENDELIAN

The overlapping phenotypes of neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD) represent the milder manifestations of the Zellweger syndrome spectrum (ZSS) of peroxisome biogenesis disorders. The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy, and visual impairment. Children with the NALD presentation may reach their teens, and those with the IRD presentation may reach adulthood (summary by Waterham and Ebberink, 2012).For a complete phenotypic description and a discussion of genetic heterogeneity of PBD(NALD/IRD), see {601539}.Individuals with mutations in the PEX16 gene have cells of complementation group 9 (CG9, equivalent to CGD). For information on the history of PBD complementation groups, see {214100}.

• Global developmental delay
• Generalized hypotonia
• Hearing impairment
• Ataxia
• Nystagmus

SOURCES: OMIM MENDELIAN

Vitamin B12-unresponsive methylmalonic acidemia type mut- is an inborn error of metabolism characterized by recurrent ketoacidotic comas or transient vomiting, dehydration, hypotonia and intellectual deficit, which does not respond to administration of vitamin B12.

VITAMIN B12-UNRESPONSIVE METHYLMALONIC ACIDEMIA TYPE MUT- Is also known as vitamin b12-unresponsive methylmalonic aciduria type mut-|partial deficiency of methylmalonyl-coa mutase

• Intellectual disability
• Seizures
• Global developmental delay
• Failure to thrive
• Muscular hypotonia

SOURCES: ORPHANET MENDELIAN