Different MUC1 gene polymorphisms in German and Japanese ethnicities affect serum KL-6 levels.

BACKGROUND

KL-6 is a high-molecular-weight glycoprotein classified as human Mucin-1 (MUC1). KL-6 has been reported to be a sensitive biomarker for interstitial lung diseases (ILDs) in the Japanese population. It is also known that polymorphisms in the MUC1 gene affect serum levels of KL-6. This study was conducted to evaluate serum levels of KL-6 and MUC1 polymorphisms in both German and Japanese populations.

METHODS

Serum levels of KL-6 were measured in 267 patients with ILDs (152 German and 115 Japanese) and 186 healthy subjects (HS) (76 German and 110 Japanese). In addition, rs4072037 single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction. The optimal cutoff values for discriminating patients with ILDs from HS was determined by receiver operating characteristic analysis based on ethnicity and rs4072037 genotypes.

RESULTS

The serum KL-6 levels in patients with ILDs were significantly higher compared with HS in both the German and the Japanese cohorts (both p<0.001). The discriminating cutoff value of serum KL-6 in the German cohort was significantly higher than the value in the Japanese cohort. The difference in the serum levels of KL-6 was significantly associated with the rs4072037 genotype distribution.

CONCLUSIONS

Even in the German cohort, the serum KL6 levels were significantly higher in patients with ILDs than HS. Because of differences in the genotype distribution of rs4072037, the KL-6 cutoff value for the German cohort that discriminated patients with ILDs from HS was significantly higher than the value in the Japanese cohort.