Features include always present findings: Scaphocephaly, Deep philtrum, Muscle fiber atrophy, and Weakness of facial musculature and others; and very common findings: Low muscle tone (hypotonia), Excessive inward curve of the lower back (lumbar hyperlordosis), and Ptosis. 38 total HPO annotations.

RYR1 function has not been fully characterized.

King-Denborough syndrome is associated with mutations in the RYR1 gene on chromosome 19.

Genetic testing for RYR1 is available. Testing is considered confirmatory for diagnosis.

Phenotype severity distribution: 20 always present features, 3 very common features, 14 common features.

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).

No clinical trials have been registered for King-Denborough syndrome.

3 publications have been identified in PubMed for King-Denborough syndrome. Research spans Epidemiology / Natural History (67%) and Case Report / Case Series (33%).

Recent Publications

• Ginsberg M (2026). [PMID: 41753076](https://pubmed.ncbi.nlm.nih.gov/41753076/). *J Clin Med*. [Epidemiology / Natural History]

• Schoonen M (2025). [PMID: 39966651](https://pubmed.ncbi.nlm.nih.gov/39966651/). *Eur J Hum Genet*. [Epidemiology / Natural History]

• Geng Z (2025). [PMID: 40410924](https://pubmed.ncbi.nlm.nih.gov/40410924/). *J Med Case Rep*. [Case Report / Case Series]