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BIOLOGY 2C03 (138)

CYP1A2 paper (1).docx

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Jurek Kolasa

Sachse et al.’s study (2003) provides a clear report of the major CYP1A2 alleles, showing that most of the allele variants do not result in a structural protein change. For example, the CYP1A2 *1F allele results from a single nucleotide polymorphism at base 164 fromAto C in the 5’non-coding region, however it does not result in a change in protein structure (Sachse, et al., 2003).As a result of the polymorphism occurring at an intron in the 5’direction, this suggests that the CYP1A2 *1F allele may be a promoter polymorphism, altering the expressivity of the CYP1A2 gene (Sachse, et al., 2003). Other allele variants including CYP1A2 *1B, *1G and *1H also result in single nucleotide substitutions (specifically a change in base T to C at position 1545), but also do not produce a structural change in the protein, and thus is a silent mutation (Sachse, et al., 2003). To study the effects of the various alleles, researchers collected urine samples to detect the caffeine 3-demethylated product, an indicator for the occurrence of caffeine metabolism (Sachse, et al., 2003). For instance, the presence of the *1F allele may result in a lower ratio of urinary caffeine to caffeine metabolites, or caffeine metabolic ratio, and thus have a tendency to result in a slower caffeine metabolism compared to that of the wild-type allele (Cornelis, El-Sohemy, Kabagambe, & Campos, 2006). In addition, studies also show that the *1Aallele may result in a higher caffeine metabolic ratio, producing a trend of higher caffeine metabolism in individuals carrying the allele ( (Nordmark, Lundgren,Ask, Granath, & Rane, 2002). Despite these trends, most published studies do not show a statistical significance between the genotype of an allele and rate of caffeine metabolism in Caucasians and other ethnicities (Nordmark, Lundgren, Ask, Granath, & Rane, 2002). Many studies show that the alleles CYP1A2 *1F and CYP1A2 *1D both illustrate a higher frequency in the population, and thus are more important for studying. In addition, allele variants *1B, *1H, *1C do not show up frequent, only occurring in less than 2% of the population in a given study (Sachse, et al., 2003). However, the allele frequencies of the CYP1A2 gene cannot be generalized for all humans for it varies between various ethnicities (Sachse, et al., 2003). Populations of Caucasians in four different studies were seen to have a higher frequency of CYP1A2 *1F alleles in the population and a lower CYP1A2 *1Aallele frequency (Nordmark, Lundgren,Ask, Granath, & Rane, 2002). However, alleles CYP1A2 *1D, *1E and *1G were approximately 8 times more frequent in studied Japanese individuals (Sachse, et al., 2003). Moreover, Egyptians were seen to have a similar CYP1A2 *1F allelic frequencies to that of Caucasians, while having a lower frequency of CYP1A2 *1C and *1E than the Japanese (Hamdy, et al., 2003). Furthermore, it was observed thatAfrican males had a higher CYP1A2 gene activity than females did (Basvi, Dandara, Bapiro, & Hasler, 2007) Hamdy, et al.’s study (2003) stated that the racial differences observed in the varying CYP1A2 activity is most likely a result of environmental and dietary factors (Hamdy, et al., 2003). First, to diagnose an individual for one of the many allelic variations to the inducibility of the CYP1A2 gene, the method of restriction fragment-length polymorphism polymerase chain reaction can be used to determine the presence of an allele (Cornelis, El-Sohemy,
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