Differences between somatic (in-site biopsies) and germ-line (peripheral blood) mutations in gastrointestinal diseases

Aims: Research protocols for the detection of disease related DNA polymorphisms is concentrating around germ-line alterations detectable in peripheral blood samples. Less is known about polymorphisms in the DNA isolated from the altered tissue biopsy.

Materials and methods: After informed consent, peripheral blood was drawn and gastric biopsy samples were taken from the pathological and healthy part of the stomach and duodenum. Genomic DNA was extracted from biopsy and blood samples from 15 patients suffered from intestinal metaplasia, 15 from ulcus duodeni, 15 from gastritis, 15 from gastric cancer, 15 from atrophia and 15 biopsy and blood samples from healthy patients. All the samples were H. pylori positive. We examined the mutations of TNF-α, IL-8, IL-1 and CD14. For the analysis of DNA samples with very low yield, a DOP-PCR amplification procedure was used.

Results: In healthy cases agreement was found between the somatic and germ-line polymorphism profile. In cases of intestinal metaplasia, atrophia a different polymorphis pattern was found in the biopsy specimen. DOP-PCR could be used for unspecific amplification of very low amount of DNA (1oo cells) yielding same results as large DNA samples.

Conclusions: For disease specific mutation analysis it can be necessary to take biopsy directly from the altered tissue and analyze the DNA isolated from it. Different somatic mutations could be found in the DNA with a different origin in a same patient.