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The genetics of alcohol metabolism: role of alcohol dehydrogenase and aldehyde dehydrogenase variants.

Edenberg HJ - Alcohol Res Health (2007)

Bottom Line: Researchers to date primarily have studied coding variants in the ADH1 B, ADH1C, and ALDH2 genes that are associated with altered kinetic properties of the resulting enzymes.For example, certain ADH1B and ADH1C alleles encode particularly active ADH enzymes, resulting in more rapid conversion of alcohol (i.e., ethanol) to acetaldehyde; these alleles have a protective effect on the risk of alcoholism.A variant of the ALDH2 gene encodes an essentially inactive ALDH enzyme, resulting in acetaldehyde accumulation and a protective effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.

ABSTRACT
The primary enzymes involved in alcohol metabolism are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Both enzymes occur in several forms that are encoded by different genes; moreover, there are variants (i.e., alleles) of some of these genes that encode enzymes with different characteristics and which have different ethnic distributions. Which ADH or ALDH alleles a person carries influence his or her level of alcohol consumption and risk of alcoholism. Researchers to date primarily have studied coding variants in the ADH1 B, ADH1C, and ALDH2 genes that are associated with altered kinetic properties of the resulting enzymes. For example, certain ADH1B and ADH1C alleles encode particularly active ADH enzymes, resulting in more rapid conversion of alcohol (i.e., ethanol) to acetaldehyde; these alleles have a protective effect on the risk of alcoholism. A variant of the ALDH2 gene encodes an essentially inactive ALDH enzyme, resulting in acetaldehyde accumulation and a protective effect. It is becoming clear that noncoding variants in both ADH and ALDH genes also may influence alcohol metabolism and, consequently, alcoholism risk; the specific nature and effects of these variants still need further study.

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Related in: MedlinePlus

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Mentions: In higher organisms, including humans, the genes encoding the various components of the body are not just simple stretches of DNA that serve as a template from which proteins are generated. Instead, they have a complex structure involving, in some cases, dozens of pieces of coding sequences interspersed with noncoding sequences. The coding sequences, which are those parts of the gene that actually serve as templates for protein production, are called exons. The intervening noncoding sequences are known as introns (see Figure). In addition to the exons and introns, genes contain regulatory sequences that determine in which cell, at what time, and in what amount the gene is actively converted into the corresponding protein (i.e., is expressed). Most of these regulatory sequences are located in front of (i.e., upstream from) the start of the coding sequences; however, other regulatory elements may be located in introns or even behind (i.e., downstream from) the coding sequences. The promoter is a set of regulatory elements located closely near the start of the gene that also specify the exact start site where conversion of the DNA template into intermediary molecules begins. However, other regulatory elements may be located quite a distance away upstream of the gene.


The genetics of alcohol metabolism: role of alcohol dehydrogenase and aldehyde dehydrogenase variants.

Edenberg HJ - Alcohol Res Health (2007)

© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3860432&req=5

Mentions: In higher organisms, including humans, the genes encoding the various components of the body are not just simple stretches of DNA that serve as a template from which proteins are generated. Instead, they have a complex structure involving, in some cases, dozens of pieces of coding sequences interspersed with noncoding sequences. The coding sequences, which are those parts of the gene that actually serve as templates for protein production, are called exons. The intervening noncoding sequences are known as introns (see Figure). In addition to the exons and introns, genes contain regulatory sequences that determine in which cell, at what time, and in what amount the gene is actively converted into the corresponding protein (i.e., is expressed). Most of these regulatory sequences are located in front of (i.e., upstream from) the start of the coding sequences; however, other regulatory elements may be located in introns or even behind (i.e., downstream from) the coding sequences. The promoter is a set of regulatory elements located closely near the start of the gene that also specify the exact start site where conversion of the DNA template into intermediary molecules begins. However, other regulatory elements may be located quite a distance away upstream of the gene.

Bottom Line: Researchers to date primarily have studied coding variants in the ADH1 B, ADH1C, and ALDH2 genes that are associated with altered kinetic properties of the resulting enzymes.For example, certain ADH1B and ADH1C alleles encode particularly active ADH enzymes, resulting in more rapid conversion of alcohol (i.e., ethanol) to acetaldehyde; these alleles have a protective effect on the risk of alcoholism.A variant of the ALDH2 gene encodes an essentially inactive ALDH enzyme, resulting in acetaldehyde accumulation and a protective effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.

ABSTRACT
The primary enzymes involved in alcohol metabolism are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Both enzymes occur in several forms that are encoded by different genes; moreover, there are variants (i.e., alleles) of some of these genes that encode enzymes with different characteristics and which have different ethnic distributions. Which ADH or ALDH alleles a person carries influence his or her level of alcohol consumption and risk of alcoholism. Researchers to date primarily have studied coding variants in the ADH1 B, ADH1C, and ALDH2 genes that are associated with altered kinetic properties of the resulting enzymes. For example, certain ADH1B and ADH1C alleles encode particularly active ADH enzymes, resulting in more rapid conversion of alcohol (i.e., ethanol) to acetaldehyde; these alleles have a protective effect on the risk of alcoholism. A variant of the ALDH2 gene encodes an essentially inactive ALDH enzyme, resulting in acetaldehyde accumulation and a protective effect. It is becoming clear that noncoding variants in both ADH and ALDH genes also may influence alcohol metabolism and, consequently, alcoholism risk; the specific nature and effects of these variants still need further study.

Show MeSH
Related in: MedlinePlus