CYSLTR1 (cysteinyl leukotriene receptor 1) is a G-protein coupled receptor located on the X chromosome X mediates immune and inflammatory responses by binding cysteinyl leukotrienes (LTC4, LTD4, LTE4) with high affinity 1. Upon LTD4 stimulation, CYSLTR1 activates phosphatidylinositol-calcium signaling cascades, triggering smooth muscle contraction and proliferation, edema, eosinophil migration, and mucus layer damage in airways [UniProt]. The receptor is highly expressed in dorsal root ganglia neurons and various immune cells during type 2 inflammation. CYSLTR1 contributes to multiple pathologies beyond classical asthma. Genetic polymorphisms in the CYSLTR1 promoter region (rs321029, rs2806489, rs7066737, rs2637204) influence transcriptional activity and predict treatment responsiveness to montelukast (a CYSLTR1 antagonist) in allergic rhinitis, independent of disease severity 2. The 927T>C polymorphism associates with combined asthma-atopic dermatitis in males 3. Recent evidence demonstrates CYSLTR1 antagonism suppresses Th17 cell differentiation via NF-κB pathway inhibition in psoriasis models 4 and inhibits uveal melanoma progression 5. Notably, CYSLTR1 emerged as a molecular target of environmental nanoplastic toxicity affecting fetal neurodevelopment 6. Distinct from CYSLTR2-mediated itch responses 7, CYSLTR1 signaling mediates bronchoconstriction and broader inflammatory pathology, positioning it as a clinically relevant therapeutic target across allergic, inflammatory, and potentially neoplastic conditions.