ORPHA:49041
IgG4-related retroperitoneal fibrosis
Also known as: Idiopathic retroperitoneal fibrosis · Ormond disease
Clinical definition (Orphanet)
A rare systemic autoimmune disease characterized by mass-forming, potentially destructive inflammation and fibrosis in the soft tissues of the retroperitoneum, associated with elevation of serum IgG4 levels and infiltration of IgG4-positive plasma cells in at least one organ or site. Most frequent locations are peripheral to the abdominal aorta, as well as the iliac and renal arteries. Clinical symptoms are unspecific and include abdominal pain, back pain, and edema of the lower extremities. The condition may occur together with IgG4-related disease in other parts of the body.
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?
7,204
7,204 papers — among the better-studied rare conditions, though still a fraction of common-disease literature (breast cancer: over 700,000). Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=183) is 38.
7,204 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).
3,009 in the last 10 years · high confidence · 98.1th percentile (publications denominator)
Is a treatment being tested?
8
trials for this specific condition
8 interventional trials matched this specific condition name; 2 currently recruiting in our sample.
Data as of 26 July 2026
8 interventional trials — more than 59.2% of diseases in the trials denominator have none at all (151 of 255; this disease is at the 84.7th percentile).
high confidence · 84.7th 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?
1,126
Distinct author names in 200 sampled papers — named people below.
Who's working on it?
People publishing on this condition (sampled Europe PMC records). Affiliation is the most recent found in that sample.
- 01Ishii H5 papers · 2026
Department of Respiratory Medicine, Fukuoka University Chikushi Hospital, Chikushino, Japan. Electronic address: hishii@fukuoka-u.ac.jp.
Papers in Europe PMC - 02Kinoshita Y5 papers · 2026
Department of Respiratory Medicine, Fukuoka University Chikushi Hospital, Chikushino, Japan.
Papers in Europe PMC - 03Kushima H5 papers · 2026
Department of Respiratory Medicine, Fukuoka University Chikushi Hospital, Chikushino, Japan.
Papers in Europe PMC - 04Li Z5 papers · 2026
Department of Clinical Laboratory, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China.
Papers in Europe PMC - 05Wang Y5 papers · 2025
Department of Rheumatology, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, Shanxi, China.
Papers in Europe PMC - 06Gao H4 papers · 2026
Department of Rheumatology and Immunology, Beijing Tsinghua Changgung Hospital, Beijing, China. gaohui_2025@163.com.
Papers in Europe PMC - 07Li Y4 papers · 2025
Department of Radiology, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China.
Papers in Europe PMC - 08Liu Y4 papers · 2025
Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.
Papers in Europe PMC - 09Wang Z4 papers · 2021
Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing, China.
Papers in Europe PMC - 10Zhang X4 papers · 2026
Department of Clinical Laboratory, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China.
Papers in Europe PMC
Recruiting interventional trials
Trials testing a treatment from the matched ClinicalTrials.gov set
8 interventional trials matched after quoted-phrase search and title/condition post-filter.
Observational and natural-history studies
5 observational studies match this condition. These do not test a treatment and are not counted in the interventional-trial headline, but they are genuine research: natural-history work often defines the endpoints needed for a future rare-disease trial, and families may be able to enroll.
Recruiting or not-yet-recruiting
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.
"IgG4-related retroperitoneal fibrosis" OR "Idiopathic retroperitoneal fibrosis" OR "Ormond disease" OR "Retroperitoneal Fibrosis"
MeSH descriptor terms unioned into the query: Retroperitoneal Fibrosis
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"IgG4-related retroperitoneal fibrosis" OR "Idiopathic retroperitoneal fibrosis" OR "Ormond disease" OR "Retroperitoneal Fibrosis"
Interventional trials matched via: both (mesh = registered under a MeSH descriptor no name phrase would catch; recall-expansion = gene / selected parent terms used only for trials).
Study-type breakdown: 8 interventional · 5 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): MESH:D012185 UMLS:C0035357 NCIT:C26876
Query health: ok — strategies attempted: phrase, mesh; with hits: phrase, mesh
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