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MYO18B
myosin XVIIIB
MYO18B is located on the long (q) arm of chromosome 22, at band 22q12.1. Arm ratio per GRCh38 - banding schematic.
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Clinical tests that include this
Overview
MYO18B encodes myosin XVIIIB, a member of the diverse myosin protein family. Myosins are molecular motors that interact with actin filaments to perform mechanical work within cells, including muscle contraction, cell division, and cargo transport. While some myosins have well-characterised functions in muscle tissue or cellular trafficking, the specific biological roles of myosin XVIIIB remain under investigation. The gene is located on chromosome 22 and produces a protein that likely participates in cytoskeletal organisation and intracellular movement, though detailed functional studies are limited compared to more extensively researched myosin family members.
What the gene does
Myosin XVIIIB belongs to the unconventional myosin class, distinguishing it from the conventional myosin II proteins primarily responsible for muscle contraction. Unconventional myosins typically function in processes such as vesicle transport, membrane trafficking, and maintenance of cellular architecture. Like other myosins, the protein is thought to hydrolyse ATP to generate force, enabling movement along actin filaments within the cytoskeleton. The specific cellular pathways in which myosin XVIIIB participates have not been fully elucidated, but structural predictions suggest it may contribute to organising the actin network or transporting cellular cargo. Research into unconventional myosins generally indicates they play specialised roles in different cell types, and myosin XVIIIB may similarly have tissue-specific or context-dependent functions that require further characterisation.
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Chromosome location
MYO18B is located on the long arm of chromosome 22 at position 12.1, designated as 22q12.1. This chromosomal region contains numerous genes, and its organisation contributes to normal cellular function. Specific details regarding the number of exons and the complete genomic structure of MYO18B have not been comprehensively catalogued in publicly available databases, reflecting the ongoing nature of genome annotation efforts for less extensively studied genes.
Protein structure
Domain architecture has not been experimentally characterised in detail for this protein.
Key variants
Genetic variants in MYO18B include sequence changes that alter the DNA code of the gene. Such variants may affect the structure or expression of myosin XVIIIB, though the clinical significance of most variants remains uncertain given limited functional data. As with many genes outside high-penetrance disease pathways, interpretation of MYO18B variants requires careful assessment of population frequency, computational predictions, and any available experimental evidence.
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.1385_1386del | p.Glu462fs | Pathogenic/Likely pathogenic | ★★☆☆ | not provided |
c.2212-1G>A | - | Pathogenic/Likely pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
c.2848C>T | p.Gln950Ter | Pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
c.2968C>T | p.Arg990Ter | Pathogenic | ★★☆☆ | Fetal anomalies with a likely genetic cause |
c.3110G>A | p.Trp1037Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
c.31G>T | p.Glu11Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
c.3880_3884del | p.Arg1294fs | Pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
c.4087C>T | p.Arg1363Ter | Pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
c.530del | p.Pro177fs | Pathogenic/Likely pathogenic | ★★☆☆ | MYO18B-related disorder |
c.6825G>A | p.Trp2275Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Klippel-Feil anomaly-myopathy-facial dysmorphism syndrome |
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
Currently, MYO18B is not definitively associated with specific inherited conditions in major clinical databases. The gene does not appear on standard diagnostic gene panels for recognised genetic disorders, suggesting that pathogenic variants have not been conclusively linked to a well-defined clinical phenotype. Further research may clarify whether variants in this gene contribute to disease, particularly as whole-genome sequencing becomes more widely applied in clinical settings.
No disease links recorded for this gene in our reference set.
UK clinical status
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the MYO18B gene do?
MYO18B encodes myosin XVIIIB, a motor protein that likely participates in cellular architecture and intracellular transport by interacting with actin filaments. Its precise biological roles remain under investigation.
Is MYO18B associated with any medical conditions?
Currently, MYO18B is not conclusively linked to specific inherited disorders in clinical databases. Further research may identify disease associations as genomic medicine advances.
Is MYO18B included in NHS genetic testing panels?
MYO18B does not currently appear on NHS Genomic Medicine Service gene panels, reflecting the absence of established clinical associations warranting routine diagnostic testing.