الفهرس 
BRONCHIAL ASTHMAOnly 14 pages are availabe for public view
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Abstract
A
sthma is a complex multifactorial disease caused by interaction of both environmental and genetic factors. The concepts underlying asthma pathogenesis have evolved dramatically in the past 25 years and are still undergoing evaluation as various phenotypes of this disease are defined and greater insight links clinical features of asthma with genetic patterns.
It is well recognized that asthma has an inheritable component to its expression, but the genetics involved in the eventual development of asthma remain a complex and incomplete picture.
To date, many genes have been found that either are involved in or linked to the presence of asthma and certain of its features.
Angiotensin-converting enzyme (ACE) gene is one of candidate genes implicated in asthma. ACE might manifest favorable effects in asthma by exhibiting its anti-inflammatory effect through the catabolization of pro-inflammatory mediators (bradykinins and tachykinins). It is also involved in the conversion of angiotensin I to the vasoactive angiotensin II which enhances proliferation and contractility of smooth muscle in the airways, thus contributing to excessive bronchoconstriction.
The insertion/deletion (I/D) polymorphism of the gene for ACE is associated with ACE plasma levels and activity. Studies have shown that the ACE insertion/deletion polymorphism has an approximately two-fold higher level of circulating enzyme as compared to individuals homozygous for the insertion polymorphism and this may potentially prevent the development of asthma or increase the severity of the disease.
The aim of this study was to investigate the frequency of ACE gene insertion/deletion polymorphism among Egyptian asthmatic patients, and to analyze the role of this polymorphism in familial aggregation as well as susceptibility of the disease.
The selected subjects in our study were divided into 2 groups:
Group I: Included 30 asthmatic patients and among them members in families with at least 2 asthmatics.
Group II: 30 healthy control individuals.
For all subjects the following were done:
• Full history taking, a thorough clinical examination,
• Pulmonary function tests (especially FEV1 and FEV1/FVC).
• Skin prick test.
• Serum total IgE.
• ACE gene polymorphism by real time PCR.
We observed from this study:
The two studied groups were comparable as regards age and gender with no significant difference between them
ACE gene polymorphism was comparable between the two studied groups with no significant difference. Regarding the patients’ genotypes, the DD genotype was slightly higher than other genotypes.
The association of other forms of atopic diseases among asthmatic patients through co-existing symptoms, skin prick test and total serum IgE level have been evaluated and then correlated with different ACE genotypes, but with no significant association.
It was proposed that the DD genotype of ACE is associated with a higher degree of severity of asthma. However, our results do not support this hypothesis because both FEV1 and FEV1/FVC ratio were not different in the patients with asthma regardless of whether they carried the DD genotype or other genotypes.
Also,the frequency of DD genotype was higher in both patients with first degree family history and those with non first degree family history of asthma and there was statistically significant difference between them.
In conclusion, although ACE gene insertion/deletion mutations influence serum ACE levels and may potentially prevent the development of asthma or increase the severity of the disease; we observed no significant difference in the genotype distributions between asthmatic patients and healthy controls.
Furthermore, ACE gene I/D polymorphism was found to be associated with genetic susceptibility to bronchial asthma with familial aggregation among Egyptian subjects.