MYH8: Myosin Heavy Chain 8
A sarcomeric myosin gene associated with Carney complex and trismus-pseudocamptodactyly syndrome
Gene Information Card
| Symbol | MYH8 |
|---|---|
| Full Name | myosin heavy chain 8 |
| Gene Type | protein-coding |
| Chromosomal Location | 17p13.1 |
| NCBI Gene ID | 4626 ncbi.nlm.nih.gov/gene/4626 |
| Ensembl ID | ENSG00000133019 |
| UniProt ID | P13535 |
| OMIM ID | 160742 |
| HGNC ID | 7578 |
| Aliases | MyHC-perinatal, MyHC-2B, MYH8A |
Description
MYH8 encodes a member of the myosin heavy chain family, specifically the perinatal isoform of skeletal muscle myosin. This protein is a major component of the sarcomere, essential for muscle contraction. Mutations in MYH8 are associated with Carney complex variant (familial cardiac myxoma) and trismus-pseudocamptodactyly syndrome (Hecht syndrome).
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Carney complex variant | Gain-of-function mutations in MYH8 lead to altered myosin ATPase activity, promoting cardiac myxoma formation | PMID: 15121796, ClinVar |
| Trismus-pseudocamptodactyly syndrome (Hecht syndrome) | Dominant-negative mutations disrupt perinatal myosin function, causing muscle contractures and limited mouth opening | PMID: 15121796, OMIM #158300 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skeletal muscle | 58.2 | High |
| Heart | 12.4 | Medium |
| Esophagus | 8.1 | Medium |
| Thyroid | 0.9 | Low |
| Brain | 0.2 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| LHCN-M2 (myoblast) | 45.6 | High expression in differentiated myotubes |
| HSMM (skeletal muscle cells) | 52.1 | High expression |
| A549 (lung) | 0.3 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.2027G>A (p.Arg676His) | Missense | Rare | Gain-of-function; associated with Carney complex |
| c.2021G>A (p.Arg674Gln) | Missense | Rare | Dominant-negative; associated with trismus-pseudocamptodactyly syndrome |
| c.2021G>C (p.Arg674Pro) | Missense | Rare | Dominant-negative; associated with trismus-pseudocamptodactyly syndrome |
Mutation functional classification
Loss of Function (LOF)
Not reported for MYH8; loss-of-function likely embryonic lethal in humans.
Gain of Function (GOF)
p.Arg676His increases myosin ATPase activity, leading to hypercontractility and cardiac myxoma.
Dominant Negative (DN)
p.Arg674Gln and p.Arg674Pro disrupt perinatal myosin function, causing muscle contractures.
View complete mutation data：
Gene Ontology (GO)
| • motor activity (GO:0003774) | • ATP binding (GO:0005524) |
| • myosin complex (GO:0016459) | • muscle filament sliding (GO:0030049) |
| • muscle contraction (GO:0006936) |
Pathways
• R-HSA-397014 – Muscle contraction
• R-HSA-445355 – Smooth muscle contraction
• R-HSA-390522 – Striated muscle contraction
Protein Summary
Myosin heavy chain 8 (MYH8) is a 1936-amino-acid sarcomeric myosin expressed predominantly in perinatal skeletal muscle and adult fast-twitch fibers. It forms the thick filament of the sarcomere and converts chemical energy from ATP hydrolysis into mechanical force for muscle contraction. Mutations in the motor domain (e.g., p.Arg674Gln) cause dominant-negative effects leading to trismus-pseudocamptodactyly syndrome, while p.Arg676His confers gain-of-function associated with Carney complex.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| MYH8 Knockout HEK293 Cell Line | EDJ-KQ4502 | Human | 4626 | Details Get a Quote |
| MYH8 Knockout HeLa Cell Line | EDJ-KQ53943 | Human | 4626 | Details Get a Quote |
| MYH8 Knockout A-549 Cell Line | EDJ-KQ62435 | Human | 4626 | Details Get a Quote |
| MYH8 Knockout HCT 116 Cell Line | EDJ-KQ70902 | Human | 4626 | Details Get a Quote |
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