ATFP: Human Consumption of Plant Foods Produced Using Genetic Engineering (GE) Technologies (2015)
Citation:
Kim SH, Kim HM, Ye YM, Kim SH, Nahm DH, Park HS, Ryu SR, Lee BO. Evaluating the allergic risk of genetically modified soybean. Yonsei Med J. 2006; 47(4): 505-512.
PubMed ID: 16941740
Study Design:
Non-Randomized Crossover Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
POSITIVE:Research Purpose:
To determine whether genetic modification increased the allergenic risk of soybeans in allergic adults who have been sensitized to soybeans.
Inclusion Criteria:
- Allergy patients 15 years old or older or healthy atopic adults
- Allergy patients had been admitted to Anjou University Hospital between August 2002 and July 2003 for treatment of various allergic problems.
Exclusion Criteria:
- Allergy patients 15 years old or younger
- Unhealthy adults.
Description of Study Protocol:
Recruitment
Recruited from hospital admission to Anjou University Hospital between August 2002 and July 2003.
Design
- Non-randomized crossover trial
- To evaluate the sensitization to GM and wild-type soybean extracts, 1,716 allergy patients and 40 healthy non-atopic subjects were enrolled by the Department of Allergy and Rheumatology, Anjou University School of Medicine, Suwon, Korea
- The GM soybean extract was Roundup Ready® into which the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene had been incorporated and the wild-type soybean extract was Daewon
- Subjects had skin prick tests (SPT) for reactions to GM and wild-type soybean extracts and to common inhaled allergens
- SPT performed on the backs of subjects and responses to 50 common allergens and 30 food allergens simultaneously. Results were read 15 minutes later and skin reactivity was expressed as the ratio of the allergen-induced wheal size to the histamine-induced wheal size.
- The presence of serum IgE specific for the soybean extracts and the EPSPS protein was determined using ELISA. Competitive ELISAs were performed to determine the specificity of IgE binding to the soybean extracts and to compare the allergenicity of the wild-type extracts, GM extracts and EPSPS.
- Analysis of antibody reactive components of the two extracts was conducted using 2D gel electrophoresis and IgE immunoblotting.
Blinding Used
Implied with measurements.
Intervention
A total of 50 common inhalant allergens and 30 food allergens including GM and wild-type soybean extracts.
Statistical Analysis
- No discussion of statistical analysis
- Percentages use to compare SPT reactions between GM and wild-type soybean extracts
- Mean values were used.
Data Collection Summary:
Timing of Measurements
All measures were conducted once:
- SPT using performed on backs of subjects using 50 common inhalant allergens and 30 food allergens
- ELISA completed to determine presence of serum IgE specific for the soybean extracts and EPSPS protein in subjects with positive skin test with A/H score of 2+
- Competitive ELISAs performed to determine specificity of IgE binding to soybean extracts and to compare allergenicity of the wild-types extracts, GM extracts and EPSPS
- Analysis of antibody reactive components of the two extracts conducted using 2D gel electrophoresis and IgE immunoblotting.
Dependent Variables
- SPT reactions
- Presence of specific IgE to soybean and EPSPS
- ELISA inhibition assays
- SDS-PAGE and IgE immunoblot analysis.
Independent Variables
A total of 50 common inhalant allergens and 30 food allergens including GM and wild-type soybean extracts.Control Variables
Quality of soybean extracts.
Description of Actual Data Sample:
- Initial N: N=1,756 subjects (1,716 allergy patients and 40 healthy non-atopic subjects)
- Attrition (final N): N=1,756 subjects
- Age: Not described; adult patients
- Location: Suwon, Korea.
Summary of Results:
Key Findings
- The IgE sensitization rates to wild-type soybeans and GM soybeans were identical (3.8% of allergic adults), and circulating IgE antibodies specific for the two extracts were comparable
- The results of the ELISA inhibition test, SDS-PAGE, and IgE immunoblotting showed a similar composition of IgE-binding components within the wild-type extracts and GM extracts, which was confirmed using two-dimensional gel electrophoresis, IgE immunoblotting and amino acid sequencing
- None of the subjects had a positive response to purified EPSPS protein in the skin prick test, ELISA or IgE immunoblot analysis.
Allergy Skin Prick Test
- A total of 65 (3.8%) of the 1,716 allergy patients had an A/H score of 2+ in response to wild-type soybean protein
- A total 66 (3.8%) of the 1,716 allergy patients had an A/H score of 2+ in response to GM soybean protein
- One allergy patient failed to respond to both the wild-type extracts and GM soybean extracts
- No subjects had a positive response to EPSPS protein.
- In subjects who had positive skin test with A/H score of 2+, prevalence of serum IgE specific for wild-type soybean and GM soybean extracts was 80% and 81%, respectively
- In subjects who had positive skin test with A/H score of 3+, 4+, 5+, prevalence of serum IgE specific for wild-type soybean and GM soybean extracts was 74% and 66%, 71% and 83% and 50% and 100%, respectively
- Levels of IgE specific for the GM soybean extracts tended to be slightly higher than those specific for the wild-type extracts and GM extracts elicited a larger wheal reaction in the SPTs
- No subjects had detectable serum IgE specific for EPSPS protein.
- In wild-type extracts, 22 protein bands (size range eight kDa to 119 kDa) were detected using the serum IgE
- In GM extracts, 20 protein bands (size range eight kDa to 119 kDa) were detected using the serum antibodies
- The 33-kDa protein was considered to be the major allergenic protein presenting in both wild-type soybean and GM soybean extracts
- No bands were detected when sera were tested against EPSPS protein.
2D gel electrophoresis and IgE immunoblot analysis of pooled sera from patients with high level of soybean-specific IgE showed that the major 33-kDa allergenic protein had a pI of 4.83 and verified that serum IgE recognized this protein.
| Allergen | Wild | GM | ||||||
| Skin reactivity score | 2+ | 3+ | 4+ | 5+ | 2+ | 3+ | 4+ | 5+ |
| Number of subjects with positive skin test | 25 | 31 | 7 | 2 | 28 | 29 | 6 | 3 |
| Specific IgE to Wild (%) | 20 (80) | 23 (74) | 5 (71) | 1 (50) | 23 (81) | 19 (66) | 5 (83) | 3 (100) |
| Specific IgE to GM (%) | 20 (80) | 23 (74) | 5 (71) | 1 (50) | 23 (81) | 19 (66) | 5 (83) | 3 (100) |
Author Conclusion:
The study demonstrates that among allergic adults in the Korean population, the prevalence of positive responses to wild-type soybean extracts and GM soybean extracts is equivalent. With the exception of one subject, all the subjects tested had a positive response to both extracts. No subjects responded to GM soybean extracts but not to wild-type extracts and no subjects responded to the EPSPS protein alone, suggesting that the protein product of the genetically introduced gene itself was not allergenic.
Funding Source:
| Not-for-profit |
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| Other: | ARCP |
Reviewer Comments:
Large sample size. Subjects were not well described.
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Quality Criteria Checklist: Primary Research
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| Relevance Questions | |||
| 1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | Yes | |
| 2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
| 3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
| 4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | Yes | |
| Validity Questions | |||
| 1. | Was the research question clearly stated? | Yes | |
| 1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
| 1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
| 1.3. | Were the target population and setting specified? | Yes | |
| 2. | Was the selection of study subjects/patients free from bias? | Yes | |
| 2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | Yes | |
| 2.2. | Were criteria applied equally to all study groups? | Yes | |
| 2.3. | Were health, demographics, and other characteristics of subjects described? | No | |
| 2.4. | Were the subjects/patients a representative sample of the relevant population? | Yes | |
| 3. | Were study groups comparable? | Yes | |
| 3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | Yes | |
| 3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | Yes | |
| 3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | Yes | |
| 3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | N/A | |
| 3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | N/A | |
| 3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
| 4. | Was method of handling withdrawals described? | Yes | |
| 4.1. | Were follow-up methods described and the same for all groups? | Yes | |
| 4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | Yes | |
| 4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
| 4.4. | Were reasons for withdrawals similar across groups? | Yes | |
| 4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | N/A | |
| 5. | Was blinding used to prevent introduction of bias? | Yes | |
| 5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | Yes | |
| 5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | Yes | |
| 5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | N/A | |
| 5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | N/A | |
| 5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
| 6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | Yes | |
| 6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | Yes | |
| 6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
| 6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | Yes | |
| 6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | Yes | |
| 6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | Yes | |
| 6.6. | Were extra or unplanned treatments described? | N/A | |
| 6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | Yes | |
| 6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
| 7. | Were outcomes clearly defined and the measurements valid and reliable? | Yes | |
| 7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
| 7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
| 7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | Yes | |
| 7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | Yes | |
| 7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
| 7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
| 7.7. | Were the measurements conducted consistently across groups? | Yes | |
| 8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | No | |
| 8.1. | Were statistical analyses adequately described and the results reported appropriately? | No | |
| 8.2. | Were correct statistical tests used and assumptions of test not violated? | No | |
| 8.3. | Were statistics reported with levels of significance and/or confidence intervals? | No | |
| 8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | N/A | |
| 8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | No | |
| 8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
| 8.7. | If negative findings, was a power calculation reported to address type 2 error? | N/A | |
| 9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
| 9.1. | Is there a discussion of findings? | Yes | |
| 9.2. | Are biases and study limitations identified and discussed? | Yes | |
| 10. | Is bias due to study's funding or sponsorship unlikely? | Yes | |
| 10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
| 10.2. | Was the study free from apparent conflict of interest? | Yes | |