MUC5B gene in a cohort of Lebanese patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the result of complex interactions between genetic and environmental factors such as cigarette smoke. MUC5B promotor polymorphism is linked to the development of sporadic forms of IPF. The reported frequency of the gene is 37,5% in sporadic IPF case subjects and 9,1% in control with an odd ratio of 9.0 in heterozygotes non-Hispanic whites and in Japanese IPF subjects its 3,4% compared to 0,8% in healthy subjects. We thought to investigate the likelihood of having the MUC5B gene in a Lebanese cohort of patients diagnosed with IPF at our center. Inclusion criteria were: a clinical diagnosis of IPF after exclusion of rheumatologic disease, a CT scan suggestive of definite or possible IPF pattern, and when available open lung biopsy consistent with IPF. Patients were consented for a finger stick blood draw for genetic testing looking for the MUC5B polymorphism rs35705950. The cohort included 32 patients and was matched with 60 normal control. MUC5B was present in 16 case subjects in heterozygote form G/T, and in 4 patients in homozygote muted T/T form. Mutation was noticed in at least one allele in 62.5% of the patients. In the control group 22 were heterozygotes G/T and one homozygote T/T out of the 60 cases, with a frequency of 38.3%. Odd ratio for disease in subjects heterozygotes for MUC5B was 3.14 Confidence Interval [1.23-8.14] p=0.008 (fisher exact test). In our IPF population MUC5B gene polymorphism frequency is 3 times more likely to be present compared to a control population, however this rate is closer to the one found in eastern Asia and much less than the one found in non-Hispanic whites.