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Quantification of PCR bias caused by a single nucleotide polymorphism in SMN gene dosage analysis.

ABSTRACT: Approximately 94% of patients with spinal muscular atrophy lack both copies of SMN1 exon 7, and most carriers have only one copy of SMN1 exon 7. We described previously the effect of SMN1/SMN2 heteroduplex formation on SMN gene dosage analysis, which is a multiplex quantitative PCR assay to determine the copy numbers of SMN1 and SMN2 using DraI digestion to differentiate SMN2 from SMN1. We describe herein the quantification of PCR bias between SMN1 exon 7 and SMN2 exon 7, which differ by only one nucleotide that is not present in either primer binding site. Using samples from 272 individuals with various SMN genotypes, we found that the amplification efficiency of SMN2 was consistent only approximately 80% that of SMN1. Thus, even a single nucleotide polymorphism, not in primer binding sites, can cause reproducible PCR bias. The precision and accuracy of our SMN gene dosage analysis are high because our assay design and controls take advantage of the consistency of the PCR bias. As additional clinically significant single nucleotide polymorphisms (SNPs) are discovered, assessment of PCR bias, and judicious selection of standards and controls, will be increasingly important for quantitative PCR assays.

SUBMITTER: Ogino S

PROVIDER: S-EPMC3278980 | biostudies-literature | 2002 Nov

REPOSITORIES: biostudies-literature

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Quantification of PCR bias caused by a single nucleotide polymorphism in SMN gene dosage analysis.

Ogino Shuji S Wilson Robert B RB

The Journal of molecular diagnostics : JMD 20021101 4

Approximately 94% of patients with spinal muscular atrophy lack both copies of SMN1 exon 7, and most carriers have only one copy of SMN1 exon 7. We described previously the effect of SMN1/SMN2 heteroduplex formation on SMN gene dosage analysis, which is a multiplex quantitative PCR assay to determine the copy numbers of SMN1 and SMN2 using DraI digestion to differentiate SMN2 from SMN1. We describe herein the quantification of PCR bias between SMN1 exon 7 and SMN2 exon 7, which differ by only on ...[more]

PMID: 12411585

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Project description:Dear Editor, The recent article by Mohammadzadeh et al.[1] on the latest issue of this Journal showed that the T allele +276G/T SNP of ADIPOQ gene is more associated with the increasing risk of coronary artery disease (CAD) in subjects with type 2 diabetes. Adipocytes were described in myocardial tissue of CAD patients and their role recently discussed[2,3]. Susceptibility to CAD by polymorphism in the Q gene of adiponectin has been reported for 3'-UTR, which harbours some genetic loci associated with metabolic risks and atherosclerosis[4]. Actually, previous studies have shown that the haplotype SNP +276G>T was associated with a decreased risk of CAD, after adjustment for potential confounding factors, therefore some controversial opinion still exists[5]. This evidence should be associated with the role exerted by adipocytes and adiponectin in heart physiology. In particular, in hypertensive disorder complicating pregnancy (HDCP), by investigating the population frequency of alleles, genotypes, and haplotypes of two single nucleotide polymorphisms (SNPs), namely +45T>G (rs2241766) and +276G>T (rs1501299), some authors found that the SNP +276 TT genotype was significantly associated with protection against HDCP, when compared to the pooled G genotypes[6]. Moreover, the same +276G/T SNP haplotype was strongly associated with biliary atresia, an intractable neonatal inflammatory and obliterative cholangiopathy, leading to progressive fibrosis and cirrhosis[7]. CAD is closely related to adiponectin biology. The same isoforms of adiponectin seem to be not associated to CAD severity but to glucose metabolism and its impairment[8]. In the paper by Mohammadzadeh et al.[1], T allele in +276G/T SNP haplotype is highly associated with CAD in subjects with type 2 diabetes, but this linkage should be reappraised if related much more to diabetes rather than CAD. Association of T allele in the indicated SNP with CAD may be an indirect consequence of type 2 diabetes, as reported by others[9] or a direct marker for CAD affected patients[10]. The paper by Mohammadzadeh et al.[1] assesses data coming elsewhere from literature but raises important concerns about the suitability of ADIPOQ SNPs in diagnosing susceptibility to CAD and the relationship with plasma adiponectin level. In normal, non diabetic, normoglycemic subject, this relationship does not seem to work. Therefore the question is how much predictive this SNP haplotype may be to foresee metabolic syndrome and CAD onset risk in young health subjects? Maybe, the role of adiponectin in cardiovascular physiology depends on its ability to target adiponectin receptors and to negatively regulate obesity. Some authors reported in healthy volunteers an absence of correlation between circulating adiponectin levels and biochemical markers, particularly lipoproteins and suggested that SNP +276G>T was related to an independent effect on adiponectin levels and on lipoprotein metabolism[11]. On the contrary, adiponectin genetic variants and SNP +276G>T was associated with increasing susceptibility of type 2 diabetes and plasma glucose impairment[12]. The interesting study by Mohammadzadeh et al.[1] suggests that SNP of ADIPOQ +276G>T should be related to susceptibility to glucose metabolism, while indirectly to lipid metabolism and fat-related cardiovascular damage.

Dataset Information

Quantification of PCR bias caused by a single nucleotide polymorphism in SMN gene dosage analysis.

Publications

Quantification of PCR bias caused by a single nucleotide polymorphism in SMN gene dosage analysis.

Similar Datasets

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