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Pontocerebellar hypoplasia type 6

Synonym(s) Fatal infantile encephalopathy with mitochondrial respiratory chain defects
Prevalence <1 / 1 000 000
Inheritance Autosomal recessive
Age of onset Infancy
  • Q04.3
  • C1969084
  • C548074
MedDRA -


Disease definition

Pontocerebellar hypoplasia type 6 (PCH6) is a rare form of pontocerebellar hypoplasia (see this term) characterized clinically at birth by hypotonia, clonus, epilepsy impaired swallowing and from infancy by progressive microencephaly, spasticity and lactic acidosis.


PCH6 is reported in less than 10 cases to date

Clinical description

PCH6 is characterized clinically at birth by generalized hypotonia, lethargy and dysphagia. The clinical profile is characterized from infancy by a profound developmental delay, progressive microencephaly, hypotonia or spasticity treatment-resistant epilepsy.


PCH6 is caused by missense and splice site mutations in the mitochondrial arginyl-transfer RNA synthetase (RARS2) gene located to 6q16.1.

Diagnostic methods

MRI demonstrates neocortical and more severe cerebral cortical atrophy (more severe than in other types of PCH), pontocerebellar hypoplasia with pons and cerebellum are equally affected. RARS2 mutation positive PCH6 patients can be screened by analysis of increased lactate in blood and cerebrospinal fluid. Biochemical analysis in muscle may demonstrate reduced activity of mitochondrial complexes I, III, and IV and normal activity of mitochondrial complex II.


Prognosis is poor, exact life expectancy is unknown but in most cases does not exceed infancy.

Expert reviewer(s)

  • Pr F. [Frank] BAAS

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