Gene ethnic variation

Gene frequencies and allelic mutations for ADH vary considerably and significant interpersonal and ethnic variations have been described. Furthermore, functional ADH is a dimer, usually of identical subunits but heterodimers are also possible and to date approximately 20 ADH isoenzymes are known. There are notable kinetic differences between the various functional ADH isoenzymes for example, Km values differ almost 1000-fold and Vmax by approximately 40-fold (see Table 6.4). These differences account, to some extent, for variation in alcohol tolerance between individuals. 

Piquet Yuria. The overall incidence of hyperphenylalaninemia is ) approximately 100 per million births, with a wide geographic and ethnic variation. PKU occnrs by antosomal recessive transmission of a defective PAH gene, cansing accnmnlation of phenylalanine in the blood well above the normal concentration in yonng children and adnlts (less than 1-2 mg/dL). In the newborn, the npper limit of normal is almost twice this valne. Valnes above 16 mg/dL are usually found in patients, snch as Piquet Yuria, with classic PKU. 

Considerable heterogeneity has been demonstrated with respect to average plasma Lp(a) levels in different ethnic groups. These differences cannot be entirely explained by differences in allele frequencies that exist between these groups [i.e., are not entirely due to allele-specific effects on Lp(a) concentrations] (M13, S3, S4). Interestingly, in the Sudanese population, Lp(a) levels are primarily (81%) determined by factors other than the size of the apo(a) allele, while in the Malay population, only 23% of the variation in Lp(a) levels could not be accounted for by size differences in the gene (S3). In Caucasians, it has previously been reported that 40-70% of the variance in Lp(a) levels can be... 

In humans, there is considerable interindividual variation in the rate, extent, and pattern of nicotine metabolism in vitro (Messina et al. 1997) and in vivo (Benowitz et al. 1994). Such variation can arise from both genetic and environmental factors. Twin studies allow an estimate of the relative contribution of heritability (i.e., contribution of genes) and environmental influences to a particular phenotype. An investigation in twins of primarily Caucasian ethnicity found that 59% of the variance in nicotine clearance can be attributed to genetic influences (Swan et al. 2005). 

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