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discussion
The results of this study demonstrate that the prevalence of positive skin-prick
tests to extracts from wild-type and GM potatoes was 5.7% in our population
of adult allergy patients. Serum-specific IgE antibodies were detected among the
positive responders. The 45-kDa allergenic band was the most frequently bound
(>80%) by the two types of extract, and ELISA inhibition studies suggested that
they had similar potencies. Recent investigations to evaluate the allergic risks of
GM corn and soybean demonstrated that allergenicity did not increase after ge-
netic manipulation of wild-type corn [11] and soybean [9]. Similarly, our study
showed that the genetic manipulation of potatoes, which are one of the most
common sources of food allergens in Korea, did not enhance their allergenic risk,
as evaluated using in vivo and in vitro methods.
GM crops currently on the market have been thoroughly assessed for safety
according to the guidelines developed by the World Health Organization [16] and
the Food and Agriculture Organization of the United Nations [17]. In addition,
the potential allergenicity of newly introduced proteins must be assessed in all
foods produced through agricultural biotechnology, and the FAO [18] and WHO
have developed a rigorous approach for this assessment. The NPTII gene intro-
duced in the potato used in this study encodes an enzyme that confers resistance
to aminoglycoside antibiotics and was isolated from the prokaryotic transposon
Tn5 [19]. The PAT gene was obtained from the aerobic soil bacterium Strepto-
myces viridochromogenes. If the gene source is bacterial, specific and targeted
serum screenings are not necessary because bacterial proteins are rarely allergenic,
due to the low exposure levels and lack of allergic sensitization to these proteins
[8]. Furthermore, previous studies have confirmed that ingestion of genetically
engineered plants expressing NPTII does not pose any safety concerns [20,21].
Herouet et al. [22] found that PAT proteins do not possess the characteristics
associated with food toxins or allergens, i.e., they have no sequence homology
with any known allergens or toxins. These findings suggest that an increase in the
allergenic risk of a GM potato is unlikely.
A few studies have identified IgE-binding components within potato extracts.
Wahl et al. [23] reported four (16, 30, 45, and 65) IgE-binding components,
which were detected by immunoblotting using sera from 12 patients with IgE-
mediated hypersensitivity reactions to potatoes. Four major potato allergens, Sol t
1 (43 kDa), 2 (21 kDa), 3 (21 kDa), and 4 (16 kDa), were identified in children
[24,25]. Furthermore, several studies have shown that allergy to natural rubber
latex is associated with cross-reactivity to potatoes and tomatoes [7,26]. In our
study of the Korean population, only one allergenic protein (45 kDa) could be
identified as the major allergen, and it was present in extracts from wild-type and
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