Author: Chu, Lai-ling
Title: Genetic predisposition to breast cancer in Chinese
Degree: M.Sc.
Year: 2001
Subject: Breast -- Cancer -- Genetic aspects
Women -- Health and hygiene
Chinese -- Health and hygiene
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Department of Nursing and Health Sciences
Pages: ix, 53, [10] leaves : ill. ; 30 cm
Language: English
Abstract: Background: The incidence of breast cancer varies among different regions of the world with the highest in America and lowest in Asia particularly in Chinese and Japanese. The difference in incidences may be explained by genetic predisposition as well as environmental or lifestyle factors. Several lines of evidence have suggested that estrogen plays a role in the pathogenesis of breast cancer. As estrogen receptor (ER) and estradiol-17 beta dehydrogenase (EDHl7B2) are involved in the biosynthesis of estrogen, they are potential candidate genes of breast cancer. Therefore the genetic susceptibility of breast cancer may be associated with estrogen receptor and estradiol-17 beta dehydrogenase genotypes. Objectives: The objectives of our study were to: 1. develop a protocol for studying estrogen receptor and estradiol-17 beta dehydrogenase genotypes using blood as the source of DNA. 2. determine genotype frequencies of estrogen receptor polymorphic site (ERcodon325) and estradiol-17 beta dehydrogenase polymorphic sites (EDHI7B2inl and EDHI7B2ex6) in breast cancer cases and non breast cancer control (aged and menopausal status matched). 3. determine if there is any association of estrogen receptor and estradiol-17 beta dehydrogenase genotypes with breast cancer. 4. determine if there is any effect of estrogen receptor and estradiol-17 beta dehydrogenase genotypes on clinical status of breast cancer in terms of tumor grade and age of onset. Design: Case control study Experimental design: One hundred and ten blood samples were taken from breast cancer patients and one hundred and ten non-breast cancer controls. DNA was extracted and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was employed to determine the genotypes of estrogen receptor, EDHI7B2inl and EDHI7B2ex6 polymorphism of the EDHI7B2 gene. The association between genotypes and breast cancer was determined by Chi square test and the relative risk was determined by odds ratio. Results: There was a significant difference between the patients and the controls in the genotype frequencies of the ER325 polymorphism (p=0.017). Women who carry at least one G allele are at increased risk for breast cancer, as the odds ratio is 1.58 with 95% confidence intervals 1.06-2.34. Our results showed that the estrogen receptor genotypes were associated with breast cancer in Chinese. No significant difference was found in two polymorphic sites (EDH17B2inl; p=0.76, EDH17B2ex6; p =0.6209) for EDH17B2 genotype frequencies among breast cancer cases and controls. Therefore, both EDHI7B2inl (odds ratio is 0.96 with 95% confidence intervals 0.70-1.53) and EDHI7B2ex6 (odds ratio is 0.98 with 95% confidence intervals 0.69-1.51) genotypes were not associated with breast cancer. Conclusions: This is the first study on genetic factors in breast cancer in Chinese patients and our data support a role of estrogen receptor in the pathogenesis of breast cancer in Chinese women. AG allele of estrogen receptor at codon 325 may confer an increased risk of cancer in Chinese women. By contrast, the EDH17B2 gene does not appear to contribute to the pathogenesis of breast cancer in Chinese.
Rights: All rights reserved
Access: restricted access

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