ORPHA:79101
Hyperprolinemia type 2
Also known as: Delta-1-pyrroline-5-carboxylate dehydrogenase deficiency
Query health: suspect — Only one of 3 strategies returned hits (phrase).
Clinical definition (Orphanet)
Hyperprolinemia type 2 is an proline metabolism disorder due to pyroline-5-carboxylate dehydrogenase deficiency. The condition is often benign but clinical signs may include , intellectual deficit and mild .
How rare: How common this is has not been clearly measured.
Is anyone studying this?
16
16 papers have ever been indexed 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.
16 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).
12 in the last 10 years · high confidence · 33.3th 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). 1 trial are registered for hyperprolinemia, the broader category — shown separately because they may or may not enrol this specific subtype.
Data as of 26 July 2026
1
trials for hyperprolinemia, 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?
Yes — we know a specific gene responsible (ALDH4A1).
GenCC classification: Definitive.
Who's working on it?
105
Distinct author names in 16 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.
- 01Ferreira CR2 papers · 2019
Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States; Rare Disease Institute, Children's National Health System, Washington, DC, United States.
Papers in Europe PMC - 02van Karnebeek CDM2 papers · 2019
Departments of Pediatrics and Clinical Genetics, Amsterdam University Medical Centers, Amsterdam, The Netherlands; Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada. Electronic address: c.d.vankarnebeek@amstedarmumc.nl.
Papers in Europe PMC - 03Akar HT1 paper · 2023
Hacettepe University Faculty of Medicine, Department of Pediatrics, Division of Pediatric Metabolism, Turkey. Electronic address: halil.tuna.akar@hacettepe.edu.tr.
Papers in Europe PMC - 04Attie AD1 paper · 2019
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Papers in Europe PMC - 05Ayzenberg I1 paper · 2019
Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Gudrunstrasse 56, 44791, Bochum, Germany.
Papers in Europe PMC - 06Bak M1 paper · 2019
Department of Clinical Genetics Copenhagen University Hospital Copenhagen Denmark.
Papers in Europe PMC - 07Barbaro M1 paper · 2019
Centre for Inherited Metabolic Diseases Karolinska University Hospital Stockholm Sweden.
Papers in Europe PMC - 08Barth M1 paper · 2021
Service de génétique médicale, CHU d'Angers, Angers, France.
Papers in Europe PMC - 09
- 10Blau N1 paper · 2018
Dietmar-Hopp Metabolic Center, University Children's Hospital, Heidelberg, Germany.
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.
1 interventional trial matched hyperprolinemia, 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.
"Hyperprolinemia type 2" OR "Delta-1-pyrroline-5-carboxylate dehydrogenase deficiency" OR "1-pyrroline-5-carboxylate dehydrogenase activity disease" OR "ALDH4A1 hyperprolinemia" OR "delta1-pyrroline-5-carboxylate dehydrogenase deficiency" OR "disorder of 1-pyrroline-5-carboxylate dehydrogenase activity" OR "hyperprolinemia caused by mutation in ALDH4A1"
MeSH descriptor terms unioned into the query: Hyperprolinemia type 2
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Hyperprolinemia type 2" OR "Delta-1-pyrroline-5-carboxylate dehydrogenase deficiency" OR "1-pyrroline-5-carboxylate dehydrogenase activity disease" OR "ALDH4A1 hyperprolinemia" OR "delta1-pyrroline-5-carboxylate dehydrogenase deficiency" OR "disorder of 1-pyrroline-5-carboxylate dehydrogenase activity" OR "hyperprolinemia caused by mutation in ALDH4A1" OR "ALDH4A1"
Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): MESH:C538385 OMIM:239510 UMLS:C2931835
Query health: suspect — strategies attempted: phrase, mesh, recall-expansion; 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