ORPHA:169799
Mild hemophilia B
Also known as: Mild congenital F9 deficiency · Mild congenital factor IX deficiency
Clinical definition (Orphanet)
A mild form of hemophilia B characterized by a small deficiency of factor IX (biological activity between 5 and 40 IU/dL) leading to abnormal bleeding as a result of minor injuries or following trauma, surgery or tooth extraction. Spontaneous hemorrhages do not occur. The condition may affect males and female carriers of disease-causing mutations.
How rare: 1-9 / 1 000 000 — roughly one to nine people per million. In a city the size of Kolkata, perhaps a few dozen.
Is anyone studying this?
141
141 papers have ever been published on this condition (under this name). For scale, breast cancer has over 700,000. Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=183) is 38.
141 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 38 (publications denominator n=183).
82 in the last 10 years · high confidence · 64.2th percentile (publications denominator)
Is a treatment being tested?
0
trials for this specific condition
No interventional trial testing a treatment matched this specific condition name on ClinicalTrials.gov (observational studies and pan-disease registries are listed separately when present). 120 trials are registered for hemophilia B, the broader category — shown separately because they may or may not enrol this specific subtype.
Data as of 26 July 2026
120
trials for hemophilia B, the broader category this belongs to
Trials registered for a broader category may or may not enrol people with this specific subtype — eligibility criteria vary, and the trial record often doesn't say. Worth raising with a clinician. How we count trials.
No matched interventional trials. This is true for 59.2% of diseases in the trials denominator (151 of 255). Here are the researchers publishing on it.
high confidence · 29.6th percentile (trials denominator)
Do we know what causes it?
Not yet — the cause hasn't been pinned down in GenCC.
No strong gene–disease assertion joined for this Orphanet entity.
Who's working on it?
789
Distinct author names in 141 sampled papers — named people below.
Who's working on it?
No interventional trial matched this name; these authors publish on it in the sampled literature — a practical starting point for contact.
- 01Bottema CD4 papers · 1991
Department of Biochemistry and Molecular Biology, Mayo Clinic/Foundation, Rochester, MN 55905.
Papers in Europe PMC - 02Fijnvandraat K4 papers · 2025
Pediatric Hematology Amsterdam UMC Emma Children's Hospital University of Amsterdam Amsterdam The Netherlands.
Papers in Europe PMC - 03Ketterling RP4 papers · 1991
Department of Biochemistry and Molecular Biology, Mayo Clinic/Foundation, Rochester, MN 55905.
Papers in Europe PMC - 04Ljung R4 papers · 2024
Department of Clinical Sciences and Paediatrics, Lund University, Lund, Sweden.
Papers in Europe PMC - 05Mancuso ME4 papers · 2023
Center for Thrombosis and Hemorrhagic Diseases, IRCCS Humanitas Research Hospital, Rozzano, 20089 Milan, Italy.
Papers in Europe PMC - 06Peyvandi F4 papers · 2025
Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, 20122 Milan, Italy.
Papers in Europe PMC - 07Sommer SS4 papers · 1991Papers in Europe PMC
- 08Königs C3 papers · 2024
Clinical and Molecular Hemostasis, Department of Pediatrics, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
Papers in Europe PMC - 09Mannucci PM3 papers · 2025
Scientific Direction, IRCCS Ca' Granda Maggiore Policlinico Hospital Foundation and University of Milan, Italy.
Papers in Europe PMC - 10Monahan PE3 papers · 2015
1 Gene Therapy Center, University of North Carolina , Chapel Hill, NC 27599.
Papers in Europe PMC
Recruiting interventional trials
Trials testing a treatment from the matched ClinicalTrials.gov set
No interventional trial testing a treatment was found for this specific condition name on ClinicalTrials.gov.
120 interventional trials matched hemophilia B, the broader category — see the summary above. Those studies are not counted in the condition-specific total.
Where to find support
We do not yet link condition-specific patient organisations. These umbrella groups support undiagnosed and ultra-rare families:
India — NPRD
Last verified 2026-07-26This ORPHAcode is not on our curated NPRD list (direct or Mondo-parent match). That does not decide clinical eligibility; families in India should ask a notified Centre of Excellence about current coverage.
Hand-curated for this project. ORPHAcode mappings are best-effort and may be incomplete or imprecise for umbrella categories. Parent (Mondo) matches mean the policy lists a broader category — confirm eligibility with a Centre of Excellence. Financial entitlements summarised from public policy statements and may change. This is not official government guidance.
How we counted this
Europe PMC query (preferred label + any corrected label + Orphanet and Mondo exact synonyms, stoplisted; unioned with resolved MeSH labels when available). UMLS / OMIM / NCIT cross-references are stored below but are not added to the query string.
"Mild hemophilia B" OR "Mild congenital F9 deficiency" OR "Mild congenital factor IX deficiency" OR "mild factor IX deficiency" OR "mild haemophilia type B" OR "mild hemophilia type B"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Mild hemophilia B" OR "Mild congenital F9 deficiency" OR "Mild congenital factor IX deficiency" OR "mild factor IX deficiency" OR "mild haemophilia type B" OR "mild hemophilia type B"
Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): UMLS:C5679574
Query health: ok — strategies attempted: phrase; with hits: phrase
Run this search on ClinicalTrials.gov
Confidence reasoning
- Preferred label is multi-word and distinctive
- No synonyms dropped by stoplist
- No label/synonym collisions with other diseases in this corpus