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SEC23B
SEC23 homolog B, COPII component
The SEC23B gene provides instructions for a protein crucial to cell transport, specifically forming COPII vesicles which are vital for moving proteins from the endoplasmic reticulum. SEC23B is a gene that codes for a component of the COPII complex, which is involved in creating small, sac-like structures called vesicles.
SEC23B is located on the short (p) arm of chromosome 20, at band 20p11.23. Arm ratio per GRCh38 - banding schematic.
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Clinical tests that include this
Overview
The SEC23B gene, also known as SEC23 homolog B, COPII component, is fundamental for intracellular transport processes. It encodes a protein that is part of the COPII (coat protein complex II) machinery, which facilitates the budding of vesicles from the endoplasmic reticulum.
These vesicles are crucial for the efficient movement of newly synthesised proteins throughout the cell and to its exterior.
What the gene does
The SEC23B gene directs the synthesis of a protein that serves as a key component of the COPII complex. This complex is instrumental in the formation of vesicles within cells, particularly originating from the endoplasmic reticulum (ER). These vesicles are specialised compartments that facilitate the transport of proteins and other essential molecules.
Specifically, the COPII complex, including the SEC23B protein, initiates the formation of these vesicles to carry proteins that are slated for secretion out of the cell. The SEC23B protein shares functional similarities with the SEC23A protein, another COPII component, suggesting some overlapping functions. However, SEC23B is thought to have a unique and critical role during the development of red blood cells, known as erythroblasts.
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Chromosome location
The SEC23B gene is situated on chromosome 20. Its specific location is at band 20p11.23. This genomic address specifies its position on the short (p) arm of chromosome 20, within region 1, band 1, and sub-band 23.
Protein structure
The SEC23B protein consists of 767 amino acids. It contains a recognised structural feature: a Gelsolin-like (Repeat) domain, spanning amino acids 634-720. This domain contributes to the protein's overall architecture and function within the COPII complex.
Key variants
Genetic variations within the SEC23B gene can influence its function, potentially affecting the efficiency of COPII vesicle formation and intracellular transport. These variations include changes in the gene's DNA sequence, which may lead to an altered or non-functional protein. Research aims to characterise how specific variants correlate with observable health outcomes.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.1015C>T | p.Arg339Ter | Pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.1243del | p.Glu415fs | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.1660C>T | p.Arg554Ter | Pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.1660del | p.Arg554fs | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.2074_2077dup | p.Asp693delinsGlyTer | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.2152C>T | p.Arg718Ter | Pathogenic/Likely pathogenic | ★★☆☆ | SEC23B-related disorder |
c.762G>A | p.Trp254Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.835-2A>G | - | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.938G>A | p.Arg313His | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
c.953T>C | p.Ile318Thr | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital dyserythropoietic anemia, type II |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Variations in the SEC23B gene have been identified in people with congenital dyserythropoietic anaemia type II. This condition is characterised by a shortage of red blood cells caused by abnormal red blood cell formation.
UK clinical status
The SEC23B gene is relevant to several clinical indications within the NHS Genomic Medicine Service. It is included on PanelApp Green lists for conditions such as congenital disorders of glycosylation, cytopenias and congenital anaemias, DDG2P, foetal anomalies (R21), likely inborn error of metabolism (R98), rare anaemia (R92), and undiagnosed metabolic disorders. This indicates that variations in SEC23B are considered medically significant for these clinical presentations in the UK.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the SEC23B gene do?
The SEC23B gene provides instructions for making a protein that is a key component of the COPII complex. This complex is responsible for forming vesicles that transport proteins from the endoplasmic reticulum to other parts of the cell or for secretion.
What condition is primarily associated with the SEC23B gene?
The SEC23B gene is primarily associated with congenital dyserythropoietic anaemia type II. This condition involves abnormal formation of red blood cells, leading to a deficiency in functional red blood cells.
Is SEC23B important for all cells?
While SEC23B plays a general role in COPII vesicle formation across various cell types, research indicates it has a particularly unique and crucial function in the development of red blood cells, specifically erythroblasts.
References
- Denecke J, Marquardt T. Congenital dyserythropoietic anemia type II (CDAII/HEMPAS): where are we now? Biochimica et biophysica acta. 2009. PMID: 19150496
- Schwarz K, Iolascon A, Verissimo F. Mutations affecting the secretory COPII coat component SEC23B cause congenital dyserythropoietic anemia type II. Nature genetics. 2009. PMID: 19561605
- Hughes H, Stephens DJ. Assembly, organization, and function of the COPII coat. Histochemistry and cell biology. 2008. PMID: 18060556
- Fromme JC, Orci L, Schekman R. Coordination of COPII vesicle trafficking by Sec23. Trends in cell biology. 2008. PMID: 18534853