CFI

Chr 4ADAR

complement factor I

Also known as: AHUS3, ARMD13, C3BINA, C3b-INA, FI, IF, KAF

This gene encodes a serine proteinase that is essential for regulating the complement cascade. The encoded preproprotein is cleaved to produce both heavy and light chains, which are linked by disulfide bonds to form a heterodimeric glycoprotein. This heterodimer can cleave and inactivate the complement components C4b and C3b, and it prevents the assembly of the C3 and C5 convertase enzymes. Defects in this gene cause complement factor I deficiency, an autosomal recessive disease associated with a susceptibility to pyogenic infections. Mutations in this gene have been associated with a predisposition to atypical hemolytic uremic syndrome, a disease characterized by acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia. Primary glomerulonephritis with immune deposits and age-related macular degeneration are other conditions associated with mutations of this gene. [provided by RefSeq, Dec 2015]

GeneReviewsOMIMResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

{Hemolytic uremic syndrome, atypical, susceptibility to, 3}MIM #612923
AD
{Macular degeneration, age-related, 13, susceptibility to}MIM #615439
AD
Complement factor I deficiencyMIM #610984
AR

Clinical highlights

Gene-disease validity (ClinGen)
atypical hemolytic-uremic syndrome · ADDefinitivesufficient evidence for diagnostic panels2 gene-disease associations curated in total
8
Active trials
2861
Pubs (1 yr)
P/LP submissions
P/LP missense
0.76
LOEUF
Multiple*
Mechanism· predicted
📖
GeneReview available — CFI
Authoritative clinical overview · Recommended first read
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Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Tolerant — LoF & missense variants common in population
LoF Constraint?
0.76LOEUF
pLI 0.000
Z-score 2.67
OE 0.51 (0.350.76)
Tolerant

Typical tolerance to LoF variation

Missense Constraint?
0.20Z-score
OE missense 0.97 (0.881.06)
298 obs / 307.9 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?
LoF OE?0.51 (0.350.76)
00.351.4
Missense OE?0.97 (0.881.06)
00.61.4
Synonymous OE?1.19
01.21.6
LoF obs/exp: 18 / 35.1Missense obs/exp: 298 / 307.9Syn Z: -1.55

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

CFI · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Clostridium Difficile InfectionVancomycin Resistant Enterococci Infection

Enteral Vancomycin as Primary Prophylaxis Against Clostridioides Difficile Infection in Critically Ill Patients

RECRUITING
NCT07221370Phase PHASE2, PHASE3Riverside University Health System Medical CenterStarted 2024-10-21
Vancomycin 125mgPlacebo
IGF1 Deficiency

Global Patient Registry to Monitor Long-term Safety and Effectiveness of Increlex® in Children and Adolescents With Severe Primary Insulin-like Growth Factor-1 Deficiency (SPIGFD).

RECRUITING
NCT00903110Esteve Pharmaceuticals, S.A.Started 2008-12-09
Increlex®
Immunoglobulin A (IgA) Nephropathy

PS-002 for the Treatment of IgA Nephropathy in Adults

RECRUITING
NCT07182227Phase PHASE1, PHASE2Purespring Therapeutics LimitedStarted 2026-03-30
PS-002
Age Related Macular Degeneration (AMD)

ORACLE: A Long-term Follow-up Study to Evaluate the Safety of GT005 in Participants With Geographic Atrophy Secondary to Age-related Macular Degeneration Treated in a Gyroscope-sponsored Antecedent Study

ENROLLING BY INVITATION
NCT05481827Phase PHASE2Gyroscope Therapeutics LimitedStarted 2022-07-12
GT005
Gonad Regulating Hormone Adverse ReactionAnalgesic Adverse ReactionDevelopmental Disability

Neurobehavioral Development in Toddlers and Preschoolers in Relation to Prenatal Exposure of Mild Analgesics (NeuroToP - a COPANA Follow up)

ENROLLING BY INVITATION
NCT07316387Rigshospitalet, DenmarkStarted 2024-05-27
UVB Phototherapy BurnInsulin-like Growth Factor 1Aging

Gene Expression Changes In Young and Geriatric Skin

RECRUITING
NCT03932162Phase EARLY_PHASE1Wright State UniversityStarted 2019-09-06
Insulin-Like Growth Factor 1No Insulin-Lie Growth Factor 1
IUGRFetal Growth RetardationIntrauterine Growth Restriction

Cardiac Displacement From Third Trimester to Early Childhood

ACTIVE NOT RECRUITING
NCT02583763University Hospital, LinkoepingStarted 2013-01
EchocardiographyBlood sample
Breast CancerDuctal CarcinomaEstrogen-receptor-positive Breast Cancer

Randomized Double-Blind Phase II Trial of Baby Exemestane Versus Baby Tamoxifen in Post-Menopausal Women at High Risk for Breast Cancer

NOT YET RECRUITING
NCT07499999Phase PHASE2Dana-Farber Cancer InstituteStarted 2026-09-09
ExemestaneTamoxifen