Skip to main content

The Glu27 genotypes of the Beta2-adrenergic receptor are predictors for severe coronary artery disease



The role of the Beta2-adrenoceptor (beta2-AR) Gln27Glu polymorphism in the manifestation of cardiovascular diseases is still unclear.


In the present study, we evaluated the potential relevance of the c.79 C>G (p.Gln27Glu) polymorphism of this receptor gene for coronary artery disease (CAD) and its associated risk factors in Saudi Arabs. Genotyping was performed by PCR using the confronting two-pair primer (PCR-CTPP) method.


In the general population group (BD) (n = 895), 68.5% were homozygous wild-type C/C, 28.3% were heterozygous C/G and 3.2% were homozygous mutant G/G. Among the CAD patients (n = 773), 50.6% were homozygous wild-type C/C, 43.6% were heterozygous C/G and 5.8% were homozygous mutant G/G, while in the angiographed control group (CON) (n = 528), 71.8% were C/C, 24.4% C/G and 3.8% G/G genotypes. These results indicate that both the C/G (p = < .001) and G/G (p = .005) genotypes are significantly associated with CAD, when compared to the CON group. In addition, C/G (p = < .001) and G/G (p = < .001) were significantly associated with CAD, when compared to the BD group. Furthermore, stepwise logistic regression showed that the genotype [C/G (p < .001) and G/G (p < .001)] increase the risk of CAD.


These results shows that the Gln27Glu genotypes (homo- or heterozygous) of the beta2-AR may be independent predictors of severe CAD.

Peer Review reports


The β2-adrenoceptor (β2-AR) plays an important role in the parasympathetic and sympathetic regulation of heart rate and contractility both in intact cardiovascular system and disease [1]. Apart from its cardiovascular function, the β2-AR also exerts vasodilatory and relaxing effects on different types of vascular smooth muscle. Hence, mutations in the gene coding for this protein are likely to have a great impact on cardiovascular reactivity and function. The gene is highly polymorphic in humans, the most common of which are the three polymorphisms Glu27, Gly16 and Thr164 that have been invariably associated with different cardiac risk factors. Besides, there is conflicting data in the literature, specifically with regard to the relevance of the Glu27 polymorphisms for the manifestation of different cardiovascular diseases and in different populations. For example, while some investigators found an association between this polymorphism and obesity in French population [2], others failed to establish such a link in various other populations [35]. Besides, the Glu27 polymorphism was associated with rheumatoid arthritis [6], coronary events in elderly patients [7], elevated leptin and triglycerides levels [8], but not with hypertension [912], blood pressure and heart size [13], obesity [5] and DM [5]. These partly conflicting reports point to the likelihood that the relevance of these gene variants as susceptibility factors for acquiring CAD or its risk factors may vary among different ethnical groups. In order to test this notion, in this study we were interested specifically in evaluating the potential relevance of the Glu27 variant for CAD manifestation and its risk factors among Arabs, using the Saudi population as a study model. Our results indicate a strong association between the C/G and G/G genotypes of the β2-AR gene and CAD in Arabs. Therefore, these genotypes (C/G or G/G) could be used as a predictor of severe CAD at least in our population.


Study population

Three groups of Saudi individuals were recruited for the present study. The patient group comprised 773 candidates (477 males and 296 females; mean age 53.8 ± 1.08 yr) of Saudi Arabian descent with angiographically documented CAD (CAD group). The inclusion criteria for severe CAD involved, among others, the presence of angiographically established narrowing of the coronary vessels by at least 70%. A second group of 528 individuals (298 males and 230 females, mean age 52.3 ± 1.42 yr) undergoing surgery for heart valvular diseases and those who reported with chest pain, but were established to have clear vessels by angiography, were recruited as controls (CON) group. A further group of 895 healthy Saudi individuals (519 males and 376 females, mean age 50.5 ± 3.6 yr) visiting the Blood Donor Clinic at King Faisal Specialist Hospital and Research Centre from January 2003 to November 2004, were recruited as representing the whole spectrum of the Saudi general population (BD group). This study was performed in compliance with the Helsinki declaration and in accordance with the regulations laid down by the Hospital Ethics Committee (approval RAC # 2010020) and all participants signed an informed consent.

Five ml of peripheral blood were collected in EDTA tubes from all participating individuals after obtaining their written consent. DNA was extracted using the PURGENE kit from Gentra Systems (Minneapolis, MN, USA), and stored in aliquots at -20°C until required. Serum cholesterol and triglyceride levels were measured as routine in the main Hospital Pathology Laboratory. Triglyceride levels < 1.8 mmol/L and total cholesterol levels < 5.2 mmol/L were considered normal. Diabetic patients either had a known history of diabetes mellitus or were diagnosed according to the American Diabetes Association criteria [14]. Diagnosis of myocardial infarction was based on the consensus specified by the European society of cardiology and the American college of cardiology [15]. Information about all risk factors was procured either through patient interviews or by referring to their medical records.

Determination of the β2-AR genotypes

The genotyping for the c.79 C>G (p.Gln27Glu) polymorphism of β2-AR was determined by polymerase chain reaction (PCR) procedure using a modified confronting two-pair primer (PCR-CTPP) method described previously [16]. As a quality control, we sequenced and confirmed the genotype status of 288 samples representing the three different genotypes.

Statistical analysis

Genotype frequencies among the various groups were compared by Chi-Square test. Multivariable logistic regression was used to study the effect of the β2-AR genotype on CAD status, incorporating other variables, such as coronary risk factors, into the model. A two-tailed p value < .05 was considered statistically significant. All analyses were performed using the SPSS v.10 (SPSS Inc., Chicago, IL, USA) statistical analysis software.


In the BD group (n = 895), 613 (68.5%) were homozygous wild-type C/C, 253 (28.3%) were heterozygous C/G and 29 (3.2%) were homozygous mutant G/G. Among the severe CAD patients (n = 773), 391 (50.6%) carried the C/C genotype, 337 (43.6%) were heterozygous C/G and 45 (5.8%) and were homozygous for the G/G genotype. Comparison of the CAD with the BD group, using the C/C wild-type genotype as the reference, both the C/G and G/G genotypes were associated with CAD (p = < .001), see Table 1. Furthermore, the frequency of the Glu27 allele (G allele) was significantly higher in the CAD group (p = < .001), Table 1.

Table 1 Genotypic and allelic distribution of the Gln27Glu polymorphism of β2-AR gene among angiographically confirmed coronary artery disease patients (CAD) and blood donors group (BD). CI, confidence interval

Among the CON group (n = 528), 379 (71.8%) were C/C, 129 (24.4%) were heterozygous C/G and 20 (3.8%) were homozygous for the G/G genotype. Comparison of the CAD and CON groups, using the C/C wild-type genotype as the reference showed that both the C/G and G/G genotypes were associated with CAD (p values of < .001 and .005, respectively), see Table 2. Furthermore, the frequency of the Glu27 allele (G allele) was significantly higher in the CAD group (p = < .001), Table 2.

Table 2 Genotypic and allelic distribution of the Gln27Glu polymorphism of β2-AR gene among angiographically confirmed coronary artery disease patients (CAD) and angiographed controls (CON). CI, confidence interval

Univariate analysis showed that β2-AR genotypes (C/G and G/G), age and diabetes mellitus were associated with CAD, whereas elevated cholesterol (p = .313), elevated triglycerides (p = .220), family history of CAD (p = .395), gender (p = .057), hypertension (p = .894) and myocardial infarction (p = .614) were not, see Table 3. Further analysis of the data based the number of vessels affected showed no association with Glu27 allele distribution among the CAD group (results not shown). The variables in Table 3, showing an association (p = < .05) were then put into a stepwise logistic regression in order to study the possible combined effect of the genotypes with other risk factors on CAD manifestation. The only variable retained in the model was the genotype (p = < .001), see Table 4, pointing to an association of the genotypes C/G (p = < .001) and G/G (p = < .001) with severe CAD manifestation.

Table 3 Determination of odds ratio for the CAD risk factors among CAD and CON groups
Table 4 Stepwise multiple logistic regression results

It is noteworthy that since the consanguinity rate in the Saudi population is > 65% [17], it was difficult for us to test for Hardy-Weinberg equilibrium because random mating among this population is not satisfied.


For determining the genotype frequencies of the β2-AR gene we selected 895 Saudi blood donors representing the whole spectrum of the Saudi population. To our knowledge this is the largest group thus far involved in studying the frequency of the β2-AR (Glu27) genotypes. The present study shows that the homozygous C/C genotype of this gene is the most predominant, while the G/G is the least prevalent in the Saudi population. The frequency of the C/G genotype (28.3%) was higher than the frequencies of 15, 16, 10, 13, 26 and 19% observed among Ghanaians, Kenyans, Sudanese, Filipinos, Indians and Chinese populations respectively [18]. However, the rate was lower than 32, 50, 53 and 48% observed among African Americans, Scottish, Caucasian USA and Swedish populations respectively [18].

The frequency for the G/G genotype was 3.2%, which is almost similar to the rate observed among Ghanaians, Filipinos and Indian populations respectively. However, our rate was lower than the rates of 21, 15, 14 and 11% observed among Scottish, Caucasian USA, Swedish and Sudanese populations respectively [18].

The observed rate of 17% for the Glu27 allele (G allele) is similar to the 21% found among the African-Americans [19], but appears to be higher than the 7 and 8% in the Chinese and Japanese [12] and lower than the frequency of 34% in Caucasian Americans [19]. Put together, these observations point to differences in the frequencies of the C/G and G/G genotypes and the Glu27 allele of the β2-AR gene among the different populations.

Our results also indicate strong association of both the C/G and G/G genotypes with the manifestation of severe CAD in Arabs. However, further studies in larger populations are required to verify these results. Nonetheless, it is noteworthy that, while this mutation has been associated with various CAD risk factors such as obesity [2], rheumatoid arthritis [6], coronary events in elderly patients [7], elevated leptin and triglycerides levels [8] in different populations, currently there is hardly any data available in the literature implicating it in the manifestation of CAD. Besides, as described previously, the data implicating different β2-AR polymorphisms in these diseases has been inconsistent, with some studies pointing to an association and others showing no relationship of these polymorphisms with various cardiovascular disorders. Our observation together with studies by other investigators furnishes support to the notion that the β2-AR Glu27 polymorphism may be invariably important for the manifestation of CAD in different populations.


In summary, our results indicate a strong association between the C/G and G/G genotypes and the Glu27 (G) allele with severe CAD in Arabs. Therefore, these genotypes (C/G or G/G) could be used as a predictor of severe CAD at least in this population.





Blood donors


Coronary artery disease




Confidence interval


Control group


Diabetes mellitus


Family history of CAD


Myocardial infarction


Polymerase chain reaction




  1. Dzimiri N: Regulation of beta-adrenoceptor signaling in cardiac function and disease. Pharmacol Rev. 1999, 51 (3): 465-501.

    CAS  PubMed  Google Scholar 

  2. Meirhaeghe A, Helbecque N, Cottel D, Amouyel P: Impact of polymorphisms of the human beta2-adrenoceptor gene on obesity in a French population. Int J Obes Relat Metab Disord. 2000, 24 (3): 382-387. 10.1038/sj.ijo.0801168.

    Article  CAS  PubMed  Google Scholar 

  3. Galletti F, Iacone R, Ragone E, Russo O, Della Valle E, Siani A, Barba G, Farinaro E, Strazzullo V, Strazzullo P: Lack of association between polymorphism in the beta2-adrenergic receptor gene, hypertension, and obesity in the Olivetti heart study. Am J Hypertens. 2004, 17 (8): 718-720. 10.1016/j.amjhyper.2004.04.012.

    Article  CAS  PubMed  Google Scholar 

  4. Kawamura T, Egusa G, Fujikawa R, Okubo M: Gln27Glu variant of the beta2-adrenergic receptor gene is not associated with obesity and diabetes in Japanese-Americans. Metabolism. 2001, 50 (4): 443-446. 10.1053/meta.2001.21695.

    Article  CAS  PubMed  Google Scholar 

  5. Duarte NL, Colagiuri S, Palu T, Wang XL, Wilcken DE: Obesity, Type II diabetes and the beta 2 adrenoceptor gene Gln27Glu polymorphism in the Tongan population. Clin Sci (Lond). 2003, 104 (3): 211-215.

    Article  CAS  Google Scholar 

  6. Xu B, Arlehag L, Rantapaa-Dahlquist SB, Lefvert AK: beta2-adrenergic receptor gene single-nucleotide polymorphisms are associated with rheumatoid arthritis in northern Sweden. Scand J Rheumatol. 2004, 33 (6): 395-398. 10.1080/03009740410010326.

    Article  CAS  PubMed  Google Scholar 

  7. Heckbert SR, Hindorff LA, Edwards KL, Psaty BM, Lumley T, Siscovick DS, Tang Z, Durda JP, Kronmal RA, Tracy RP: Beta2-adrenergic receptor polymorphisms and risk of incident cardiovascular events in the elderly. Circulation. 2003, 107 (15): 2021-2024. 10.1161/01.CIR.0000065231.07729.92.

    Article  CAS  PubMed  Google Scholar 

  8. Rosmond R, Ukkola O, Chagnon M, Bouchard C, Bjorntorp P: Polymorphisms of the beta2-adrenergic receptor gene (ADRB2) in relation to cardiovascular risk factors in men. J Intern Med. 2000, 248 (3): 239-244. 10.1046/j.1365-2796.2000.00721.x.

    Article  CAS  PubMed  Google Scholar 

  9. Bengtsson K, Orho-Melander M, Melander O, Lindblad U, Ranstam J, Rastam L, Groop L: Beta(2)-adrenergic receptor gene variation and hypertension in subjects with type 2 diabetes. Hypertension. 2001, 37 (5): 1303-1308.

    Article  CAS  PubMed  Google Scholar 

  10. Jia H, Sharma P, Hopper R, Dickerson C, Lloyd DD, Brown MJ: beta2-adrenoceptor gene polymorphisms and blood pressure variations in East Anglian Caucasians. J Hypertens. 2000, 18 (6): 687-693. 10.1097/00004872-200018060-00005.

    Article  CAS  PubMed  Google Scholar 

  11. Castellano M, Rossi F, Giacche M, Perani C, Rivadossi F, Muiesan ML, Salvetti M, Beschi M, Rizzoni D, Agabiti-Rosei E: Beta(2)-adrenergic receptor gene polymorphism, age, and cardiovascular phenotypes. Hypertension. 2003, 41 (2): 361-367. 10.1161/01.HYP.0000052831.85600.79.

    Article  CAS  PubMed  Google Scholar 

  12. Kato N, Sugiyama T, Morita H, Kurihara H, Sato T, Yamori Y, Yazaki Y: Association analysis of beta(2)-adrenergic receptor polymorphisms with hypertension in Japanese. Hypertension. 2001, 37 (2): 286-292.

    Article  CAS  PubMed  Google Scholar 

  13. Busjahn A, Li GH, Faulhaber HD, Rosenthal M, Becker A, Jeschke E, Schuster H, Timmermann B, Hoehe MR, Luft FC: beta-2 adrenergic receptor gene variations, blood pressure, and heart size in normal twins. Hypertension. 2000, 35 (2): 555-560.

    Article  CAS  PubMed  Google Scholar 

  14. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care. 2003, 26 (Suppl 1): S5-20.

  15. Alpert JS, Thygesen K, Antman E, Bassand JP: Myocardial infarction redefined – a consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the redefinition of myocardial infarction. J Am Coll Cardiol. 2000, 36 (3): 959-969. 10.1016/S0735-1097(00)00804-4.

    Article  CAS  PubMed  Google Scholar 

  16. Hamajima N, Saito T, Matsuo K, Kozaki K, Takahashi T, Tajima K: Polymerase chain reaction with confronting two-pair primers for polymorphism genotyping. Jpn J Cancer Res. 2000, 91 (9): 865-868.

    Article  CAS  PubMed  Google Scholar 

  17. Panter B: Parental responses to consangunity and genetic disease in Saudi Arabia. Soc Sci Med. 1991, 33: 1295-1302. 10.1016/0277-9536(91)90078-Q.

    Article  Google Scholar 

  18. Maxwell TJ, Ameyaw MM, Pritchard S, Thornton N, Folayan G, Githang'a J, Indalo A, Tariq M, Mobarek A, Evans DA, et al: Beta-2 adrenergic receptor genotypes and haplotypes in different ethnic groups. Int J Mol Med. 2005, 16 (4): 573-580.

    CAS  PubMed  Google Scholar 

  19. Xie HG, Stein CM, Kim RB, Gainer JV, Sofowora G, Dishy V, Brown NJ, Goree RE, Haines JL, Wood AJ: Human beta2-adrenergic receptor polymorphisms: no association with essential hypertension in black or white Americans. Clin Pharmacol Ther. 2000, 67 (6): 670-675. 10.1067/mcp.2000.106293.

    Article  CAS  PubMed  Google Scholar 

Pre-publication history

Download references


This work was supported by the "Research Center of King Faisal Specialist Hospital & Research Center", project # 2010020/RAC. We thank all the participants for taking part in this study.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Khaled K Abu-Amero.

Additional information

Competing interests

The author(s) declare that they have no competing interests.

Authors' contributions

KKA was in charge of design and analysis of data, OMA performed the technical aspects of the study, PCR and genotyping, GHM performed the statistical analysis and ND was responsible for recruiting patients and overall supervision of the study.

Rights and permissions

Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Reprints and permissions

About this article

Cite this article

Abu-Amero, K.K., Al-Boudari, O.M., Mohamed, G.H. et al. The Glu27 genotypes of the Beta2-adrenergic receptor are predictors for severe coronary artery disease. BMC Med Genet 7, 31 (2006).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: