GENE REFERENCE / HGNC:16133

TBC1D20

TBC1 domain family member 20

protein-coding gene20p13Gene information

What does this gene do?

The TBC1D20 gene provides instructions for making a protein that helps regulate the activity of other proteins called GTPases, which control a variety of functions in cells. Often referred to as molecular switches, GTPases can be turned on and off. They are turned on (active) when they are attached (bound) to a molecule called GTP and are turned off (inactive) when they are bound to another molecule called GDP. The TBC1D20 protein turns off a GTPase known as RAB18 by stimulating a reaction that turns the attached GTP into GDP. When active, RAB18 is involved in a process called vesicle trafficking, which moves proteins and other molecules within cells in sac-like structures called vesicles. RAB18 regulates the movement of substances between compartments in cells and the storage and release of fats (lipids) by structures called lipid droplets. The protein also appears to play a role in a process called autophagy, which helps clear unneeded materials from cells. RAB18 is important for the organization of a cell structure called the endoplasmic reticulum, which is involved in protein processing and transport.

The TBC1D20 protein is also thought to inactivate another GTPase called RAB1. RAB1 is important for maintaining the structure of a cell compartment called the Golgi apparatus, in which newly produced proteins are modified so they can carry out their functions. The TBC1D20 protein also appears to play a role in the copying (replication) of viruses in infected cells.

Source: MedlinePlus, National Library of Medicine. Source publication: 2020-08-18. Source review: 2018-04.

ClinGen reviews

We found no matching ClinGen review in the data used here. This does not rule out a link between the gene and a condition.

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: 281
Submissions for variants in or overlapping this gene: 358
Submissions explicitly reporting this gene: 270
Alleles reported pathogenic / likely pathogenic: 11
VariationIDs with uncertain significance: 107
VariationIDs with conflicting classifications: 2

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 TBC1D20?

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 11 alleles in TBC1D20 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 TBC1D20.

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

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