Shared Enrichment of the MUC5B Variant rs35705950 in Idiopathic Pulmonary Fibrosis and Fibrotic Hypersensitivity Pneumonitis: Evidence from a Russian Cohort

Background/Objectives: The MUC5B rs35705950 polymorphism is the strongest common genetic risk factor for idiopathic pulmonary fibrosis (IPF), whereas its role in fibrotic hypersensitivity pneumonitis (fHP) remains incompletely characterized, particularly in Eastern European cohorts. This study aimed to evaluate the distribution of MUC5B rs35705950 genotypes and alleles in Russian patients with IPF and fHP and to assess their association with disease susceptibility using a large external Russian reference dataset.