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Features include always present findings: Microcephaly and Intellectual disability; and very common findings: Large hands, Mild intellectual disability, Long face, and Broad nasal tip and others. 25 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Head and neck | 6 | Cleft palate, Microcephaly, Long face |
Brain and nerves | 4 | Delayed speech and language development, Mild intellectual disability, Intellectual disability |
Arms and legs | 3 | Large hands, Long toe, Preaxial hand polydactyly |
Bones and joints | 2 | Thoracic kyphosis, Sideways curvature of the spine (scoliosis) |
PHF8 function has not been fully characterized.
Syndromic X-linked intellectual disability Siderius type is caused by mutations in the PHF8 gene on chromosome X.
Genetic testing for PHF8 is available. Testing is considered confirmatory for diagnosis.
Phenotype severity distribution: 2 always present features, 6 very common features, 4 common features.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for syndromic X-linked intellectual disability Siderius type.
6 publications have been identified in PubMed for syndromic X-linked intellectual disability Siderius type. Research spans Basic Science / Preclinical (50%), Review / Meta-Analysis (33%), and Case Report / Case Series (17%).
Kremp M (2026). [PMID: 40145966](https://pubmed.ncbi.nlm.nih.gov/40145966/). *Neural Regen Res*. [Basic Science / Preclinical]
Artes MH (2026). [PMID: 41714361](https://pubmed.ncbi.nlm.nih.gov/41714361/). *EMBO Rep*. [Basic Science / Preclinical]
Rezazadeh S (2025). [PMID: 40469903](https://pubmed.ncbi.nlm.nih.gov/40469903/). *Front Mol Neurosci*. [Review / Meta-Analysis]
Hussain SI (2024). [PMID: 38956580](https://pubmed.ncbi.nlm.nih.gov/38956580/). *BMC Med Genomics*. [Case Report / Case Series]
Horsthemke B (2024). [PMID: 38854642](https://pubmed.ncbi.nlm.nih.gov/38854642/). *Med Genet*. [Review / Meta-Analysis]
Kremp M (2024). [PMID: 38613395](https://pubmed.ncbi.nlm.nih.gov/38613395/). *Glia*. [Basic Science / Preclinical]
Data assembled from 7 of 12 sources · Last updated Sep 19, 2026, 6:55 PM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center