| Research Abstract |
Diffuse panbronchiolitis (DPB), relatively popular among non-smoker adults in Japan, is characterized by chronic inflammation located in respiratory bronchioles, causing obstructive respiratory failure with persistent pseudomonas infection, and frequent complication with chronic sinusitis. Recent elucidation of the genetic defect in a putative chloride ion channel gene, cystic fibrosis transmembrane conductance regulator (CFTR), among patients with cystic fibrosis (CF) who shares resembling clinical features with DPB led us to examine possible genetic defects in CFTR gene among patients with DPB in Japan. The Cystic Fibrosis Genetic Analysis Consortium accumulated and reported almost 300 sequence alterations in the CFTR gene, frequently associated with exons consisting peptides of putative functional domains of CFTR protein. In this context, we examined, in the 1st year, exons 4,7,10,11,19,20 among 27 exons in CFTR gene where genetic defects are highly accumulated, and then extended to
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all exons in the 2nd year. DNA fragments were amplified by polymerase chain reaction using genomic DNAs from 18 patients with DPB (age 18 - 74; 11 males, 7 females). The fragments were then subjected to electrophoresis for single strand conformational polymorphism (SSCP). In exons 12 and 18, two different SSCPs' were found in 3 cases, and in 3 and 24, single SSCP was found in 2 cases, respectively. In exons 9,11,19,21,22, and 24, single SSCP was detected in one case. In exons 6b,9,10, and 24, there found SSCPs' with patterns of homozygous and heterozygous bands, suggesting the existence of normal variant polymorphism. In exons 2,4,5,7,8,13,14a,14b,15,17b,20, and 23, no SSCP was detected in all 18 cases. Exons 1,13,16,and 17a should be analyzed by direct sequencing. These results indicate that the genetic defects in patients with DPB in Japan may not be related to the CFTR gene, because no common SSCP bands was found among 18 patients, although direct sequencing of all CFTR exons in one or two patients is necessary to neglect false negatives due to SSCP procedure. Less
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