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Disease Profile

Pontocerebellar hypoplasia type 6

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
<1 / 1 000 000

< 331

US Estimated

< 514

Europe Estimated

Age of onset

Infancy

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ICD-10

Q04.3

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Encephalopathy fatal infantile with mitochondrial respiratory chain defects

Categories

Congenital and Genetic Diseases; Metabolic disorders; Nervous System Diseases

Summary

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
orphanet

Orpha Number: 166073

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.

Epidemiology
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.

Etiology
PCH6 is caused by missense and splice site mutations in the mitochondrial arginyltransfer 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
Prognosis is poor, exact life expectancy is unknown but in most cases does not exceed infancy.

Visit the Orphanet disease page for more resources.

Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
Percent of people who have these symptoms is not available through HPO
Absent speech
Absent speech development
Lack of language development
Lack of speech
No speech development
No speech or language development
Nonverbal

[ more ]

0001344
Apnea
0002104
Atrophy/Degeneration affecting the brainstem
0007366
Autosomal recessive inheritance
0000007
Cerebellar atrophy
Degeneration of cerebellum
0001272
Cerebellar hypoplasia
Small cerebellum
Underdeveloped cerebellum

[ more ]

0001321
Cerebral atrophy
Degeneration of cerebrum
0002059
Congenital onset
Symptoms present at birth
0003577
Death in childhood
0003819
Deeply set eye
Deep set eye
Deep-set eyes
Sunken eye

[ more ]

0000490
Failure to thrive
Faltering weight
Weight faltering

[ more ]

0001508
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
Global developmental delay
0001263
Hyperreflexia
Increased reflexes
0001347
Increased CSF lactate
0002490
Increased serum lactate
0002151
Lower limb spasticity
0002061
Narrow forehead
Decreased width of the forehead
0000341
Narrow palate
Narrow roof of mouth
0000189
Poor head control
0002421
Poor suck
Poor sucking
0002033
Progressive
Worsens with time
0003676
Progressive microcephaly
Progressively abnormally small cranium
Progressively abnormally small skull

[ more ]

0000253
Prominent nasal bridge
Elevated nasal bridge
High nasal bridge
Prominent bridge of nose
Prominent nasal root
Protruding bridge of nose
Protruding nasal bridge

[ more ]

0000426
Seizure
0001250
Upper limb spasticity
Uncontrollable movement in upper arms
0006986
Variable expressivity
0003828

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

    Organizations

    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Organizations Providing General Support

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

        • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

          In-Depth Information

          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Pontocerebellar hypoplasia type 6. Click on the link to view a sample search on this topic.