C5AR1

Chr 19

complement C5a receptor 1

Also known as: C5A, C5AR, C5R1, CD88

Enables G protein-coupled receptor activity and complement component C5a receptor activity. Involved in several processes, including complement component C5a signaling pathway; mRNA transcription by RNA polymerase II; and positive regulation of ERK1 and ERK2 cascade. Located in apical part of cell and basolateral plasma membrane. Biomarker of Alzheimer's disease; asthma; chronic obstructive pulmonary disease; rhinitis; and severe acute respiratory syndrome. [provided by Alliance of Genome Resources, Jul 2025]

OMIMResearchGenerating clinical summary…
MultiplemechanismLOEUF 1.70
Clinical SummaryC5AR1
Population Constraint (gnomAD)
Constrained for loss-of-function variants (OE-LoF 0.00) despite low pLI — interpret in context.

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Tolerant — LoF & missense variants common in population
LoF Constraint?
1.70LOEUF
pLI 0.402
Z-score 0.96
OE 0.00 (0.001.70)
Tolerant

Highly tolerant — LoF variants common in population

Missense Constraint?
0.16Z-score
OE missense 0.97 (0.871.09)
211 obs / 217.6 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?
LoF OE?0.00 (0.001.70)
00.351.4
Missense OE?0.97 (0.871.09)
00.61.4
Synonymous OE?1.08
01.21.6
LoF obs/exp: 0 / 1.1Missense obs/exp: 211 / 217.6Syn Z: -0.67

This gene — mechanism propensity

DN
0.76top 25%
GOF
0.77top 25%
LOF
0.2387th %ile

This gene has evidence for multiple mechanisms of pathogenicity (gain-of-function and dominant-negative). Both the Badonyi & Marsh prediction and the broader genomic evidence point to gain-of-function as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.

GOFprediction above median
DNprediction above median

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

C5AR1 · 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

No active trials found for this gene.

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