MUC1 and pulmonary alveolar proteinosis: The frequency of MUC1 rs4072037 SNP genotype was significantly different between PAP patients and healthy controls (PAP: A/A 46 %, A/G 54 % and G/G 0 %; healthy controls: A/A 30, A/G 40 and G/G 30 %, p = 0.013) (Fig. 2).