Genomic organization and polymorphisms of the major house dust mite allergen Der f2

We amplified genomic DNA encoding the major house dust mite allergen, Der f2, from Dermatophagoides farinae by means of the polymerase chain reaction and cloned it into Escherichia coli. The nucleotide sequences of the amplified fragments were determined and compared with those of the cDNA previously reported. Four Der f2 genomic clones were obtained, suggesting that the genomic Der f2 gene had sequence polymorphisms like the cDNA clones. Each of the genomic clones had a single small intron. With respect to the exon sequences, two of the four genomic clones were identical with two cDNA clones, respectively. The others were combinations of the two clones. Genomic Southern blotting suggested that the Der f2 gene is located at one locus in the mite genome and that sequence substitutions were due to polymorphisms among individual mite genes.