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Hoyeraal-Hreidarsson syndrome (HHS) is a very rare X-linked recessive disorder considered to be a severe variant of dyskeratosis congenita characterized by intrauterine growth retardation, microcephaly, cerebellar hypoplasia, progressive combined immune deficiency and aplastic anemia.
Features include very common findings: Microcephaly, Intellectual disability, Global developmental delay, and Cerebellar hypoplasia and others; and common findings: Hypertonia, Low red blood cell count (anemia), Blood clotting problems (abnormality of coagulation), and Enlarged brain ventricles (ventriculomegaly) and others. 28 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 7 |
Biomarker and diagnostic research for Hoyeraal-Hreidarsson syndrome has been reported in the published literature.
Phenotype severity distribution: 10 very common features, 12 common features.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
3 clinical trials registered, 2 recruiting. Interventions under study include drug therapy, procedural interventions, and biologic therapy. Pipeline includes 2 PHASE2, 1 PHASE1. Research is primarily sponsored by academic and government institutions.
112 publications have been identified in PubMed for Hoyeraal-Hreidarsson syndrome. Research spans Review / Meta-Analysis (42%), Basic Science / Preclinical (26%), and Case Report / Case Series (11%).
Research Type | Count | % of Total |
|---|---|---|
Research summaries | 41 |
Data assembled from 5 of 12 sources · Last updated Sep 20, 2026, 4:52 AM UTC
European rare disease database
Genetic and Rare Diseases Info Center
Common questions about Hoyeraal-Hreidarsson syndrome
Blood and immune system | 6 | Low platelet count (thrombocytopenia), Abnormal leukocyte morphology, Low red blood cell count (anemia) |
Growth and development | 3 | Failure to thrive, Intrauterine growth retardation, Short stature |
Skin | 3 | Excessive wrinkled skin, Generalized hyperpigmentation, Nail dystrophy |
Muscles | 2 | Cerebral cortical atrophy, Dermal atrophy |
Head and neck | 1 | Microcephaly |
Neoplasm | 1 | Neoplasm |
Bones and joints | 1 | Bone marrow hypocellularity |
42%
Laboratory research | 25 | 26% |
Patient case studies | 11 | 11% |
Disease patterns and progression | 7 | 7% |
Testing and diagnosis research | 5 | 5% |
New treatment approaches | 5 | 5% |
Clinical study results | 2 | 2% |
Other research | 1 | 1% |
Yogeshwar SM (2026). [PMID: 40650880](https://pubmed.ncbi.nlm.nih.gov/40650880/). *Brain : a journal of neurology*. [Basic Science / Preclinical]
Rheault MN (2026). [PMID: 40938675](https://pubmed.ncbi.nlm.nih.gov/40938675/). *Journal of the American Society of Nephrology : JASN*. [Basic Science / Preclinical]
Senoo N (2026). [PMID: 41847620](https://pubmed.ncbi.nlm.nih.gov/41847620/). *iScience*. [Basic Science / Preclinical]
Chang K (2025). [PMID: 39934534](https://pubmed.ncbi.nlm.nih.gov/39934534/). *Clinical reviews in allergy & immunology*. [Review / Meta-Analysis]
Sergi CM (2025). [PMID: 40386366](https://pubmed.ncbi.nlm.nih.gov/40386366/). *Translational pediatrics*. [Epidemiology / Natural History]
Mondschein AS (2025). [PMID: 40522084](https://pubmed.ncbi.nlm.nih.gov/40522084/). *Journal of the peripheral nervous system : JPNS*. [Basic Science / Preclinical]
Omri S (2025). [PMID: 40058592](https://pubmed.ncbi.nlm.nih.gov/40058592/). *Journal of lipid research*. [Diagnostic / Biomarker]
Jones-Weinert C (2025). [PMID: 39614014](https://pubmed.ncbi.nlm.nih.gov/39614014/). *Nature reviews. Molecular cell biology*. [Review / Meta-Analysis]
Hingar S (2025). [PMID: 40409799](https://pubmed.ncbi.nlm.nih.gov/40409799/). *Advances in genetics*. [Review / Meta-Analysis]
Romagnani P (2025). [PMID: 40053507](https://pubmed.ncbi.nlm.nih.gov/40053507/). *Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association*. [Review / Meta-Analysis]