GENE REFERENCE / HGNC:30348

POLR3B

RNA polymerase III subunit B

protein-coding gene12q23.3Gene information

What does this gene do?

The POLR3B gene provides instructions for making one part (subunit) of an enzyme called RNA polymerase III. This enzyme is involved in the production (synthesis) of ribonucleic acid (RNA), a chemical cousin of DNA. The RNA polymerase III enzyme attaches (binds) to DNA and synthesizes RNA in accordance with the instructions carried by the DNA, a process called transcription. RNA polymerase III helps synthesize several forms of RNA, including ribosomal RNA (rRNA) and transfer RNA (tRNA). Molecules of rRNA and tRNA assemble protein building blocks (amino acids) into working proteins; this process is essential for the normal functioning and survival of cells.

Source: MedlinePlus, National Library of Medicine. Source publication: 2020-08-18. Source review: 2013-06.

ClinGen reviews

ClinGen reviews the evidence linking a particular gene to a condition. Each rating below describes the strength of that link. It does not classify a variant in your DNA file.

Condition	Inheritance	Evidence
POLR3B-related disorderMONDO:0700277 · Evaluated 2025-09-03	Autosomal recessive	DefinitiveLeukodystrophy and Leukoencephalopathy Gene Curation Expert Panel
POLR3B-related disorderMONDO:0700277 · Evaluated 2025-09-03	Autosomal dominant	DefinitiveLeukodystrophy and Leukoencephalopathy Gene Curation Expert Panel

ClinVar records

These numbers show what has been submitted to ClinVar. They cannot tell you how likely you are to have a condition.

Submitted alleles: 851
Submissions for variants in or overlapping this gene: 1,393
Submissions explicitly reporting this gene: 1,329
Alleles reported pathogenic / likely pathogenic: 87
VariationIDs with uncertain significance: 395
VariationIDs with conflicting classifications: 41

The rows count different things: alleles, submissions or VariationIDs. Their categories can overlap, so do not add them together. Pathogenic/likely pathogenic counts exclude structural variants that merely overlap a gene. A dash in the source means “not reported,” not zero.

NCBI produces the gene-summary file each week using counts recorded at the start of the month. The numbers may differ from those on the live ClinVar website. Read the field definitions ↗

View this gene in ClinVar ↗

YOUR DNA FILE

Can your DNA file tell you about POLR3B?

From a DNA test kit (such as 23andMe, AncestryDNA or MyHeritage). These kits check a fixed list of about 600,000 to 700,000 positions across your whole genome. ClinVar lists 87 alleles in POLR3B reported as pathogenic or likely pathogenic. A kit checks only some of these positions, and often none of them.

From whole genome sequencing (a VCF file). Sequencing reads most of your genome. Your file lists the places where your DNA differs from the reference genome. Some regions are hard to sequence, including parts of some genes that have near-identical copies elsewhere, and a VCF file does not record which positions were read well.

If a variant is not in your file, that does not mean you don’t have it.

What BioDecode checks

BioDecode compares every variant in your file with ClinVar, on your own computer. For each match, it shows the ClinVar classification, the review status and the condition it was reported for. Your file is not uploaded.

A ClinVar classification applies to one particular variant and the condition it was reported for. It does not tell you about other variants in POLR3B.

BioDecode cannot fill gaps in your test, diagnose a condition or replace clinical testing.

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