Variation in gene copy number and polymorphism of the human salivary amylase isoenzyme system in Caucasians

Abstract

Summary. The polymorphic patterns of human salivary amylase of a large number of individuals of Caucasian origin were determined by using isoelectric focusing and polyacrylamide gel electrophoresis. Nine different salivary amylase protein variants were found; three of them are recorded for the first time and their heredity is shown. Some of the variants are encoded by haplotypes expressing three allozymes. Most variants display low frequencies. Analysis of the relative intensities of variant-specific isozyme bands, combined with segregation analysis, show that extensive quantitative variation is present in the population. The numbers of salivary amylase genes in some families showing quantitative variation at the protein level have been estimated by the polymerase chain reaction. We present evidence that quantitative variations in amylase protein patterns do not always reflect variations in gene copy number but that other mechanisms are also involved.

Individual Differences in AMY1 Gene Copy Number, Salivary α-Amylase Levels, and the Perception of Oral Starch

“…For example, a significant amount of variation in protein amount and activity was not explained by AMY1 gene copy number (R 2  = 0.25 and 0.27, respectively) in this study. Our finding is consistent with previous research [8], [9], which suggests that amylase expression may reflect additional genetic influences, such as nonsynonymous single nucleotide polymorphisms (SNPs) in the AMY1 gene (three known nonsynonymous SNPs) or differences in the transcription or translation efficiency between AMY1 genes in different haplotypes [9]. Furthermore, nongenetic influences, including stress and dietary starch intake, may additionally affect protein levels.…”

“…In addition, there is evidence that salivary amylase expression is upregulated by a diet high in starch [7]. Genetically, salivary amylase levels are influenced by individual copy number variation (CNVs) of the AMY1 gene on chromosome 1p21, which codes for salivary amylase [8]. The AMY1 gene is one of the most variable CNV loci in the human genome, with a reported range of anywhere from 2 to 15 diploid copies.…”

The Importance of Dietary Carbohydrate in Human Evolution

“…Humans are unusual in that they have high levels of the salivary ␣-amylase, apparently due mostly to multiple copies of AMY1 genes. Among primates, multiple copy numbers of AMY1 genes have been identified only in H. sapiens (Groot et al 1989b;Bank et al 1992;Samuelson et al 1996). Furthermore, a strong correlation has been shown between AMY1 copy number and the concentration of amylase in saliva (Bank et al 1992;Perry et al 2007) as well as oral starch digestion rate (Mandel et al 2010).…”

“…Among primates, multiple copy numbers of AMY1 genes have been identified only in H. sapiens (Groot et al 1989b;Bank et al 1992;Samuelson et al 1996). Furthermore, a strong correlation has been shown between AMY1 copy number and the concentration of amylase in saliva (Bank et al 1992;Perry et al 2007) as well as oral starch digestion rate (Mandel et al 2010). Young infants, prior to weaning in particular, who have a greater requirement for preformed glucose (Bier et al 1999) and for whom salivary amylases have greater importance in starch digestion , may have benefitted from multiple copies of the AMY1 genes.…”

Great genotypic and phenotypic diversities associated with copy-number variations of complement C4 and RP-C4-CYP21-TNX (RCCX) modules: A comparison of Asian-Indian and European American populations

“…Such concept of constant gene copy-numbers is being gradually revised in the past twenty years, albeit unnoticeably. For examples, complement C4 and amylase manifest frequent and heritable gene copy-number variations among different healthy individuals (Bank et al , 1992;Blanchong et al , 2000;Carroll et al , 1984;Chung et al , 2002a;Dangel et al , 1994;Perry et al , 2007;Shen et al , 1994;Wu et al , 2007;Yang et al , 2003;Yang et al , 2007;Yang et al , 1999;Yu, 1991;Yu et al , 2003;Yu and Campbell, 1987). Recent advent of whole genome microarray studies and personal genomic DNA sequencing revealed numerous genomic loci with duplications of DNA segments > 1 kb in size; many of those segments contain protein-coding genes (Lupski, 2007;McCarroll, 2008;Redon et al , 2006;Sebat et al , 2004).…”