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Thread: Types of genetic variations

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    PharmD Year 1 TomHsiung's Avatar
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    Default Types of genetic variations

    The types of genetic variations include single-nucleotide polymorphisms, insertion-deletion polymorphisms, tandem repeats, frameshift mutation, defective splicing, aberrant splice site, premature stop codon polymorphisms, and copy number variants.
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease.

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    PharmD Year 1 TomHsiung's Avatar
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    SNP

    Single-nucleotide polymorphisms, abbreviated as SNPs and pronounced "snips," are the most common genetic variations in human DNA, occurring once approximately every 300 base pairs. SNPs are single-base differences that exist between individuals. Nucleotide substitution results in two possible alleles. One allele, typically either the most commonly occurring allele or the allele originally sequenced, is considered the wide type, and the alternative allele is considered the variant allele.



    A SNP may result in amino acid substitution, which may or may not alter the function of the encoded protein. For example, in the figure above, guanine (G) is substituted for adenine (A) at nucleotide 46 in the beta-2-adrenergic receptor gene. This results in the substitution of glycine for arginine at amino acid position (codon) 16 and alterations in receptor downregulation upon prolonged exposure to beta2-receptor agonists.

    SNPs that result in amino acid substitution are referred to as nonsynonymous. SNPs that do not result in amino acid substitution are called synonymous.

    For instance, the codon is GGA and the SNP that the replacement of adenine (A) with cytosine (C) is synonymous since GGA and GGC are both codon for glycine, and there should be no amino acid substitution.
    Last edited by TomHsiung; Wed 19th March '14 at 9:48pm.
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease.

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    PharmD Year 1 TomHsiung's Avatar
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    Terminology of SNP

    Synonymous SNPs usually are abbreviated based on the nucleotides involved and the nucleotide base position. For example, 1166A>C indicates that either adenine or cytosine may occur, with adenine occurring most often at position 1166 of a given gene region.

    Nonsynonymous SNPs usually are designated by the amino acids and codon involved. For example, Arg16Gly indicates that glycine may be substituted for arginine at codon 16.
    Last edited by TomHsiung; Wed 19th March '14 at 9:57pm.
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease.

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    Quote Originally Posted by TomHsiung View Post
    SNP

    Single-nucleotide polymorphisms, abbreviated as SNPs and pronounced "snips," are the most common genetic variations in human DNA, occurring once approximately every 300 base pairs. SNPs are single-base differences that exist between individuals. Nucleotide substitution results in two possible alleles. One allele, typically either the most commonly occurring allele or the allele originally sequenced, is considered the wide type, and the alternative allele is considered the variant allele.



    A SNP may result in amino acid substitution, which may or may not alter the function of the encoded protein. For example, in the figure above, guanine (G) is substituted for adenine (A) at nucleotide 46 in the beta-2-adrenergic receptor gene. This results in the substitution of glycine for arginine at amino acid position (codon) 16 and alterations in receptor downregulation upon prolonged exposure to beta2-receptor agonists.

    SNPs that result in amino acid substitution are referred to as nonsynonymous. SNPs that do not result in amino acid substitution are called synonymous.

    For instance, the codon is GGA and the SNP that the replacement of adenine (A) with cytosine (C) is synonymous since GGA and GGC are both codon for glycine, and there should be no amino acid substitution.
    It was really very useful information for me. This was the best example to know the about the synonymous and nonsyninymous. The main difference is with amino acid.
    Last edited by Preciousbaker; Mon 25th August '14 at 2:42pm.

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