Gene
POLR3B
RNA polymerase III subunit B
- HGNC 30348(opens in a new tab)
- Ensembl gene ENSG00000013503(opens in a new tab)
- NCBI Gene 55703(opens in a new tab)
Summary
- Cytogenetic location
- 12q23.3
- Coordinates
- Chromosome 12: 106,357,748–106,510,198 (GRCh38)
- Exons
- 28 exons across 152.5 kb
- Protein
- 1,133 amino acids
- Inheritance
- Autosomal recessive
- Also known as
- RPC2, FLJ10388, C128
- MANE Select transcript
- ENST00000228347.9NM_018082.6
- Locus type
- gene with protein product
- Very high
- Confident
- Low
- Very low
Reference genomeGRCh38hg38
Positions on gene and variant pages follow this choice, in this browser.
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Get my Genome TestCurated reports relevant to this gene
Pelizaeus-Merzbacher Disease & Hypomyelinating Leukodystrophies
- POLR3-related (4H) leukodystrophyAutosomal recessive
Changes in POLR3A, POLR3B, POLR1C or POLR3K cause hypomyelination with problems of balance and coordination, often with dental anomalies and delayed puberty (hypomyelination, hypodontia and hypogonadotropic hypogonadism).
- 4 GenCC submitters rate it definitive or strong
What knowing changes
Diagnosis allows monitoring of dental development and puberty, and hormone treatment where needed.
Broader groupings
Charcot-Marie-Tooth Disease
One of 62 genes linked to it
A group of inherited peripheral neuropathies causing progressive weakness and wasting of the distal muscles and loss of sensation, mainly in the feet and hands.
- 2 GenCC submitters rate it definitive or strong
What knowing changes
Genetic counseling, subtype-specific monitoring, physical therapy, orthotics, neurotoxic drug avoidance, gene-specific clinical trials, surveillance for associated features
Other Inherited Leukodystrophies
- Leukodystrophy (other and unspecified types)
One of 80 genes linked to it
Inherited conditions that damage or prevent the normal formation of myelin, the white matter of the brain and spinal cord. Different types follow autosomal recessive, autosomal dominant or X-linked inheritance depending on the gene involved.
- 4 GenCC submitters rate it definitive or strong
What knowing changes
Knowing the specific genetic cause can end a diagnostic search, guide supportive care and surveillance, show whether a specific treatment exists, and allow testing of relatives.
Inheritance
- Autosomal recessive
- It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.
How POLR3B is laid out
- Coding sequence
- Untranslated region
- Intron
- Direction of transcription
- Known disease-causing sites
- Stretches short reads find hard
Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.
Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).
Nearby genes from Ensembl release 116, on GRCh38.
Exons make up 4.2 kb of the gene's 152.5 kb; 3,402 of those bases code for the protein.
How a genome test reads POLR3B
54
positions in POLR3B where ClinVar classes a change as pathogenic or likely pathogenic
None of them falls in a region short reads find hard.
A whole genome covers all 152.5 kb of POLR3B, introns included, not only the 4.2 kb of exons.
Traits linked to POLR3B
The Human Phenotype Ontology lists these as features of the rare conditions POLR3B can cause. Each trait's page lists the other genes linked to it.
Abnormality of the nervous system
- Abnormal pyramidal sign
- Ataxia
- Cerebellar vermis atrophy
- CNS hypomyelination
- Degeneration of cerebellum
- Delayed speech and language development
- Difficulty articulating speech
- Difficulty performing quick and alternating movements
Show 28 more traits
- Dystonia
- Global developmental delay
- Inability to coordinate movements when walking
- Intellectual disability
- Lack of coordination of movement
- Leukodystrophy
- Loss of developmental milestones
- Thin corpus callosum
- Tremor
- Underdevelopment of part of brain called corpus callosum
- Demyelinating peripheral neuropathy
- Intention tremor
- Babinski sign
- Delayed ability to walk
- Epilepsy
- Impaired distal proprioception
- Impaired distal vibration sensation
- Increased reflexes
- Intellectual disability, mild
- Loss of ability to walk
- Chiari type I malformation
- Decreased reflex response
- Delayed CNS myelination
- IQ between 34 and 49
- Peripheral neuropathy
- Cerebral hypomyelination
- Decrease in size of the outer layer of the brain due to loss of brain cells
- Postural tremor
External links
Gene records
Transcript
Protein
Where this comes from
- HGNC: the gene's symbol, name, other symbols and location.
- MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
- GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
- The ACMG secondary findings list, SF v3.2.
- ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
- The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
- Data release 2026.10.16-c6eea6bf.
Cite this page
Dante Labs. (n.d.). POLR3B gene: RNA polymerase III subunit B. Retrieved 17 October 2026, from https://dantelabs.com/genes/polr3b
Dante Labs. POLR3B gene: RNA polymerase III subunit B [Internet]. [cited 17 October 2026]. Available from: https://dantelabs.com/genes/polr3b
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