ORPHA:91498
Familial congenital palsy of trochlear nerve
Query health: suspect — Only one of 3 strategies returned hits (recall-expansion).
Clinical definition (Orphanet)
A rare, genetic, neuro-ophthalmological disease characterized by fourth cranial nerve palsy, manifesting with hypertropia in side gaze, unexplained head tilt, acquired vertical diplopia, and increase in vertical fusional vergence amplitudes with prolonged occlusion. Facial asymmetry (i.e. hemifacial retrusion, upward slanting of mouth on the side of the head tilt, mild enophthalmos of paretic eye) and superior oblique tendon abnormalities (such as absence, redundance, misdirection) are frequently associated. Some asymptomatic cases have been reported.
How rare: <1 / 1 000 000 — fewer than one in a million. In a city the size of Kolkata, that might mean on the order of fifteen people.
Is anyone studying this?
0
We found no papers under this exact name — work may still exist under another label.
0 in the last 10 years · low confidence
Is a treatment being tested?
0
trials for this specific condition
No interventional trial testing a treatment matched this specific condition name. 1 observational study did — shown below because natural-history and cohort work can be an important step toward a trial.
Data as of 26 July 2026
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.
low 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?
0
Distinct author names in 0 sampled papers.
Who's working on it?
No author names could be extracted from the sampled publications. Try the Europe PMC query in “How we counted this,” or contact an umbrella rare-disease organisation for researcher referrals.
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.
See who's working on it above — people publishing on this disease are often the practical next contact when no trial is listed.
Observational and natural-history studies
1 observational study matches 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.
None of the matched observational studies is currently listed as 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.
"Familial congenital palsy of trochlear nerve" OR "hereditary fourth cranial nerve palsy"
MeSH descriptor terms unioned into the query: fourth cranial nerve palsy, familial congenital
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Familial congenital palsy of trochlear nerve" OR "Familial congenital palsy of the trochlear nerve" OR "hereditary fourth cranial nerve palsy" OR "fourth cranial nerve palsy, familial congenital" OR "congenital trochlear nerve palsy" OR "oculomotor nerve paralysis" OR "fourth cranial nerve palsy"
Study-type breakdown: 0 interventional · 1 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): MESH:C565007 OMIM:136480 UMLS:C1850996
Query health: suspect — strategies attempted: phrase, mesh, recall-expansion; with hits: recall-expansion
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
- Zero publications but parent term hereditary neurological disease has 123 — literature likely indexed under a broader name