The allele-specific probe and primer amplification assay, a new real-time PCR method for fine quantification of single-nucleotide polymorphisms in pooled DNA

The evolution of fungicide resistance within populations of plant pathogens must be monitored to develop management strategies. Such monitoring often is based on microbiological tests, such as microtiter plate assays. Molecular monitoring methods can be considered if the mutations responsible for resistance have been identified. Allele-specific real-time PCR approaches, such as amplification refractory mutation system (ARMS) PCR and mismatch amplification mutation assay (MAMA) PCR, are, despite their moderate efficacy, among the most precise methods for refining SNP quantification. We describe here a new real-time PCR method, the allele-specific probe and primer amplification assay (ASPPAA PCR). This method makes use of mixtures of allele-specific minor groove binder (MGB) TaqMan probes and allele-specific primers for the fine quantification of SNPs from a pool of DNA extracted from a mixture of conidia. It was developed for a single-nucleotide polymorphism (SNP) that is responsible for resistance to the sterol biosynthesis inhibitor fungicide fenhexamid, resulting in the replacement of the phenylalanine residue (encoded by the TTC codon) in position 412 of the enzymatic target (3-ketoreductase) by a serine (TCC), valine (GTC), or isoleucine (ATC) residue. The levels of nonspecific amplification with the ASPPAA PCR were reduced at least four times below the level of currently available allele-specific real-time PCR approaches due to strong allele specificity in amplification cycles, including two allele selectors. This new method can be used to quantify a complex quadriallelic SNP in a DNA pool with a false discovery rate of less than 1%.     

Analysis of Genetic Polymorphism of Deoxyribonuclease I in Ovambo and Turk Populations Using a Genotyping Method

Deoxyribonuclease I (DNase I) polymorphism has been used as a valuable marker in genetic and clinical investigations. Six codominant alleles are known for DNase I, DNASE1*1, *2, *3, *4, and the recently discovered alleles *5 and *6. To detect these two new alleles, we added a new DNase I genotyping method based on both an allele-specific amplification and mismatched polymerase chain reaction (PCR). These methods were used to examine the distribution of DNase I genotypes in unrelated individuals from bloodstains of Ovambo and Turkish populations. The DNASE1*1 allele was found to be most dominant in the Ovambos. In contrast, Turks showed the highest allele frequency for DNASE1*2. This study is the first to demonstrate that there is a certain genetic heterogeneity in the worldwide distribution of DNase I polymorphism using the genotyping method of human DNase I polymorphism with PCR.     

A Unique Primer with an Inosine Chain at the 5′-Terminus Improves the Reliability of SNP Analysis Using the PCR-Amplified Product Length Polymorphism Method

Polymerase chain reaction-amplified product length polymorphism (PCR-APLP) is one of the most convenient and reliable methods for single nucleotide polymorphism (SNP) analysis. This method is based on PCR, but uses allele-specific primers containing SNP sites at the 3′-terminus of each primer. To use this method at least two allele-specific primers and one “counter-primer”, which serves as a common forward or reverse primer of the allele-specific primers, are required. The allele-specific primers have SNP sites at the 3′-terminus, and another primer should have a few non-complementary flaps at the 5′-terminus to detect SNPs by determining the difference of amplicon length by PCR and subsequent electrophoresis. A major disadvantage of the addition of a non-complementary flap is the non-specific annealing of the primer with non-complementary flaps. However, a design principle for avoiding this undesired annealing has not been fully established, therefore, it is often difficult to design effective APLP primers. Here, we report allele-specific primers with an inosine chain at the 5′-terminus for PCR-APLP analysis. This unique design improves the competitiveness of allele-specific primers and the reliability of SNP analysis when using the PCR-APLP method.     

Thr21Met (T21M) but not Ser89Asn (S89N) polymorphisms of the urotensin-II (UTS-II) gene are associated with Behcet's disease (BD)

Behcet's disease (BD) is multisytemic vasculitis or chronic inflammation that may lead to various autoimmune and autoinflammatory syndromes. Exact etiopathogenesis of BD has not been clarified yet. Urotensin II (UTS-II) is predominantly a vasoactive peptide and Thr21Met polymorphism in UTS-II gene was proved to increasing in some autoimmune diseases. Considering these, our objective was to evaluate whether two UTS-II gene polymorphisms (Thr21Met and Ser89Asn) were responsible in genetic susceptibility to BD in a Turkish population. A total of 198 patients with BD and 275 healthy controls were enrolled. We analyzed the genotype and allele frequencies of two UTS-II gene polymorphisms, Thr21Met and Ser89Asn, in BD patients and in controls. We found that Thr21Met but not Ser89Asn polymorphisms of the UTS-II gene were markedly associated with the risk of developing BD (p < 0.0001), The Met21Met genotype was less common among BD patients (6.1% in patients vs. 17.1% in controls; p < 0.0001). There was also an increase in the 21Thr allele (54.8% in BD patients vs. 43.8% in controls) and a decrease in 21Met allele frequencies (45.2% in controls vs. 56.2% in patients) in the BD groups (p < 0.0044). To the best of our knowledge, for the first time in the literature, our study claims that there is an association between Thr21Met, and not between Ser89Asn polymorphisms in the UTS-II gene and BD. These results put a new player to the field of undiscovered pathogenesis of BD and hopefully provide new insights to the treatment options.     

High-throughput SNP genotyping by single-tube PCR with Tm-shift primers

Despite many recent advances in high-throughput single nucleotide polymorphism (SNP) genotyping technologies, there is still a great need for inexpensive and flexible methods with a reasonable throughput. Here we report substantial modifications and improvements to an existing homogenous allele-specific PCR-based SNP genotyping method, making it an attractive new option for researchers engaging in candidate gene studies or following up on genome-wide scans. In this advanced version of the melting temperature (Tm)-shift SNP genotyping method, we attach two GC-rich tails of different lengths to allele-specific PCR primers, such that SNP alleles in genomic DNA samples can be discriminated by the Tms of the PCR products. We have validated 306 SNP assays using this method and achieved a success rate in assay development of greater than 83% under uniform PCR conditions. We have developed a standalone software application to automatically assign genotypes directly from melting curve data. To demonstrate the accuracy of this method, we typed 592 individuals for 6 SNPs and showed a high call rate (>98%) and high accuracy (>99.9%). With this method, 6-10,000 samples can be genotyped per day using a single 384-well real-time thermal cycler with 2-4 standard 384-well PCR instruments.     

A single nucleotide polymorphism genotyping method using phosphate-affinity polyacrylamide gel electrophoresis

To date, various methods have been developed to facilitate the genotyping of a single nucleotide polymorphism (SNP) for aiding in the diagnosis and treatment of inherited diseases. The most commonly used method for SNP genotyping is an allele-specific hybridization procedure using an expensive fluorochrome-labeled oligonucleotide probe and a specialized fluorescence analyzer. Here, we introduce a simple and reliable genotyping method using a 1:1 mixture of 5'-phosphate-labeled and nonlabeled allele-specific polymerase chain reaction (PCR) primers. The method is based on the difference in mobility of the phosphorylated and nonphosphorylated PCR products (in the same number of basepairs) on phosphate-affinity polyacrylamide gel electrophoresis. The phosphate-affinity site is a polyacrylamide-bound dinuclear zinc(II) complex, which preferentially captures the 5'-phosphate-labeled allele-specific product compared with the corresponding nonlabeled product. The obtained DNA migration bands can be visualized by ethidium bromide staining. We demonstrate the genotyping of a SNP reported in a human cardiac sodium channel gene, SCN5A, using this novel procedure.     

Refinement of single-nucleotide polymorphism genotyping methods on human genomic DNA: amplifluor allele-specific polymerase chain reaction versus ligation detection reaction-TaqMan

Single-nucleotide polymorphisms (SNPs) have proven to be powerful genetic markers for a variety of genetic applications, e.g., association studies leading to dissection of both monogenetic and complex diseases. However, no single SNP genotyping method has been broadly accepted. In the present study, we compared and refined two promising methods with potential for research and for diagnostic SNP genotyping: Amplifluor allele-specific polymerase chain reaction (PCR) and ligation detection reaction (LDR)-TaqMan. The methods are based on allele-specific primer extension and allele-specific ligation, respectively. Since LDR-TaqMan had previously been tested on just Arabidopsis thaliana, we adjusted the method for the more complex human genome. Amplifluor allele-specific PCR has a single-step and closed-tube format, whereas the LDR-TaqMan assay comprises two simple steps. Contrary to the primer-extension-based method, the ligation-based method can be multiplexed. Refining the LDR-TaqMan technique, we successfully replaced a previously suggested three-step multiplexing procedure with a less laborious two-step approach. Comparing refined LDR-TaqMan with Amplifluor allele-specific PCR in a family-based study, both techniques appeared similar with respect to high robustness and accuracy. As both approaches utilize primers with common tails, all SNPs can be assayed with the same couple of fluorescence reporting reagents, ensuring low establishing and running expenses.     

Influences of the N700S thrombospondin-1 polymorphism on protein structure and stability

Thrombospondins (THBSs) are multimodular, secreted proteins characterized by a signature domain comprising a unique set of 13 calcium-binding repeats flanked by epidermal growth factor (EGF)-like and lectin-like modules. A polymorphism that changes a conserved Asn to Ser at residue 700 in the most N-terminal calcium-binding repeat of THBS-1 (repeat 1C) is found in 8-10% of European populations and has been linked to increased risk of premature coronary artery disease. The Ser substitution leads to altered stability in the EGF-like and wire modules of the THBS-1 signature domain as assessed by differential scanning calorimetry carried out in 2 mm or 200 mum calcium. Studies of the melting profiles of the THBS-2 signature domain proteins with Asn or Ser at position 702 (homologous to 700 in THBS-1) revealed that the impact of the Ser allele is similar in both THBS-1 and THBS-2. Structure determination of the Ser(702) THBS-2 variant in 2 mm calcium showed that repeat 1C contains two bound calcium ions as in the crystal of the Asn(702) protein, including the ion that is coordinated by Asn(702), and is associated with changes in conformation of repeat 1C and the adjacent EGF-like modules. The Ser substitution leads to the decreased ability of soluble THBS-2 signature domain protein to bind 4B6.13, a conformation-sensitive monoclonal antibody that recognizes an epitope in repeat 1C. These results indicate that although THBS harboring the Ser allele binds a full complement of calcium ions, repeat 1C is altered, leading to destabilization of surrounding structures.     

LDL-R and Apo-B-100 gene mutations in Polish familial hypercholesterolemias

A group of 30 Polish families with clinical signs of familial hypercholesterolemia was studied for the presence of germ-line mutations in the LDL-R and ApoB-100 genes. Screening of the LDL-R gene was performed at the genomic DNA level by single-strand conformation polymorphism analysis of all 18 exons and extended by sequencing of polymerase chain reaction (PCR) products showing abnormalities. The occurrence of large LDL-R gene alterations was evaluated by analysis of restriction enzyme patterns on Southern blots and using the long-PCR technique. The ApoB-100 gene was studied by combined allele-specific and asymmetric PCR for the occurrence of the common B-3500 missense mutation G to A at nucleotide position 10,708. Germ-line mutations were found in 17 families. In 12 of them LDL-R gene mutations were detected. Three of 11 different mutations had previously been described in other populations (3-bp deletion of codon 197; Ser156Leu; Gly571Glu). Of the mutations not previously recognized and identified in Polish families, there were three small deletions (2-bp deletion AG at codon 291; 4-bp deletion CCCT at codons 661–662; 1-bp deletion A at codon 830), and four point mutations (Arg239Stop, Cys331Stop, Asn543Ser, Gln665Stop). Additionally, one large (∼1-kb) LDL-R gene deletion between exons 6 and 9 was identified. In five families, the B-3500 mutation within the ApoB-100 gene was revealed. Received: 15 September 1997 / Accepted: 10 February 1998     

A microarray-based high throughput molecular marker genotyping method: the tagged microarray marker (TAM) approach

A microarray-based method has been developed for scoring thousands of DNAs for a co-dominant molecular marker on a glass slide. The approach was developed to detect insertional polymorphism of transposons and works well with single nucleotide polymorphism (SNP) markers. Biotin- terminated allele-specific PCR products are spotted unpurified onto streptavidin-coated glass slides and visualised by hybridisation of fluorescent detector oligonucleotides to tags attached to the allele- specific PCR primers. Two tagged primer oligonucleotides are used per locus and each tag is detected by hybridisation to a concatameric DNA probe labelled with multiple fluorochromes.     

Both antiviral activity and intracellular localization of chicken Mx protein depend on a polymorphism at amino acid position 631

The Mx protein is known to inhibit the multiplication of several RNA viruses. In chickens, a polymorphism at amino acid position 631 (631 aa) of Mx protein has been suggested to be involved in the antiviral ability against vesicular stomatitis virus (VSV) and influenza virus, indicating that a Ser-to-Asn substitution at 631 aa is the source of this antiviral ability. However, how the substitution at 631 aa contributes to the antiviral activity remains to be clarified. In this study, we investigated differences in antiviral activity against VSV and intracellular localization between Ser and Asn types at 631 aa of the chicken Mx protein. The results showed that chicken Mx protein with an Asn at 631 aa inhibited VSV multiplication and Mx distribution in a granular-like pattern in the cytoplasm. However, Mx carrying the Ser type did not inhibit viral growth and homogenous spread throughout the cytoplasm. Furthermore, we found that replacing Ser with Asn at 631 aa provided Mx with antiviral activity against VSV, with Mx showing granular-like distribution in the cytoplasm. These results demonstrated that a single amino acid polymorphism at 631 aa of the chicken Mx protein altered both the antiviral activity and intracellular localization.     

Touchdown thermocycling program enables a robust single nucleotide polymorphism typing method based on allele-specific real-time polymerase chain reaction

Different methods have been developed for single nucleotide polymorphism (SNP) typing during recent years. Allele-specific polymerase chain reaction (ASPCR) is a cost-saving method that scores SNPs by difference of the PCR efficiency of allele-specific primers. However, ASPCR for SNP typing is notoriously confounded for its locus-specific unpredictability and the laborious gel electrophoresis. In the current study, we investigated the real-time kinetics of ASPCR and found that a simple touchdown thermocycling protocol improved its specificity significantly. Combined with real-time PCR, we developed a homogeneous genotyping method and scored more than 1000 genotypes, including all transition and transversion SNPs. A clear genotyping result was identified and validated the robustness of the method. Optimization of reactions and intrinsic modification of allele-specific primers, a laborious process but one that is repeatedly reported to be inevitable for successful ASPCR, was proved to be unnecessary with our method. Accuracy was confirmed with mass spectrometry. These characters enabled real-time ASPCR with the touchdown thermocycling protocol being very competitive among various SNP typing methods for large-scale genetic studies.     

Allele-specific amplification of exon 7 in the survival motor neuron (SMN) genes for molecular diagnosis of spinal muscular atrophy

There are two highly homologous survival motor neuron (SMN) genes in humans but molecular defects in the SMN1 gene cause spinal muscular atrophy (SMA). More than 90% of SMA patients are shown to have a homozygous deletion of exon 7 in the SMN1 gene. Therefore, a simple test for exon 7 deletion would be very useful in the molecular diagnosis of SMA. However, limited methods are available, and most of these methods utilize expensive instruments and consumables. Here, we describe a simple allele-specific PCR test, which can be performed using standard equipment in DNA laboratories. The principle of the test is based on a single nucleotide difference (C versus T) between the exon 7 of SMN1 and SMN2 genes. Using allele-specific primers, two PCR amplifications are performed for each sample to amplify a 404-bp diagnostic fragment, and consequent electrophoresis of PCR products on agarose gel provides definitive information concerning the exon 7 deletion To rule out false negatives, a 500-bp fragment from the N-acetyltransferase gene was coamplified as an internal control in each test. We have, so far, analyzed 41 SMA samples with our method, and tested the validity of results using an independent restriction fragment length polymorphism (RFLP) method. Genotyping results obtained by both methods were in complete agreement for all of the samples analyzed. Our method can also be used to detect heterozygous deletion of exon 7 in SMN genes, if the relative intensities of the diagnostic and internal control bands are determined.     

Frequency distribution of single nucleotide polymorphisms in P-selectin gene in Chinese Tibetan and Han populations

Background

Chinese Tibetans have a series of distinctive physiological traits which enable them to tolerate the extreme environment of the Tibetan plateau. P-selectin gene has been proved to be highly polymorphic in Europeans and Americans. Nevertheless, studies on either the frequency distributions of single nucleotide polymorphisms (SNPs) or haplotype diversity and linkage disequilibrium of P-selectin gene in Chinese Tibetan population are still unavailable.

Methods

The frequency distributions of 3 SNPs in P-selectin gene promoter (− 2123C/G, − 1969A/G, − 1817T/C) and 3 SNPs in exon region (Ser290Asn, Val599Leu, Thr715Pro) were investigated by real-time PCR and high-resolution melting method among 314 Chinese Tibetans and 328 age- and sex-matched Han people.

Results

The frequencies of the − 2123G and − 1817T alleles among the Tibetan population had no significant differences from those of the Han population. Among the Tibetan population, the G allele frequency of − 1969A/G and Ser290Asn were both higher than those of the Han population. Val599Leu and Thr715Pro did not show any polymorphism in the two populations. In the Tibetan population, − 2123C/G, − 1969A/G, − 1817T/C and Ser290Asn were in tight linkage disequilibrium with each other.

Conclusions

The frequency distributions of − 1969A/G and Ser290Asn polymorphisms in the Tibetan population were different from those in the Han population.     

Melanocortin-4 Receptor Gene Polymorphisms in Obese Patients

Obesity is a complex disease caused by both genetics and environmental factors. Melanocortin-4 receptor (MC4R) (MIM 155541) gene polymorphisms were reported to be the cause of monogenic obesity in humans. We studied three polymorphisms (Val50Met, Val103Ile, and Ser58Cys) and a mutation (Asn274Ser) of the MC4R gene in 203 obese patients and in 110 healthy subjects in the Turkish population. A high incidence of Val103Ile and Val50Met polymorphisms as well as the Asn274Ser mutation was found in the obese patients, whereas no significant correlation was found regarding the Ser58Cys polymorphism. We conclude that there is a concordance between the polymorphisms (Val103Ile, Val50Met, Ser58Cys) that were first studied in the Turkish population with obesity.     

Comparison of PCR-RFLP with allele-specific PCR in genetic testing for spinal muscular atrophy

PCR-based methods for the detection of homozygous deletion of exon 7 of the SMN1 gene have been widely used in genetic testing for spinal muscular atrophy (SMA). We compared the most commonly used PCRrestriction fragment length polymorphism (PCR-RFLP) assay with an allele-specific PCR method, evaluating their potential application in direct testing, prenatal prediction, and preimplantation diagnosis, in terms of a range of DNA amounts used in such testing. We showed that PCR-RFLP could identify the SMN1 exon 7 by amplifying 10 pg of genomic DNA, and could differentiate SMN1 from SMN2 at the 100-pg DNA level (DraIdigested SMN2 fragments served as an internal control for PCR efficiency). In contrast, allele-specific PCR for SMN1, despite some advantages in a rapid preimplantation diagnosis, quickly lost its specificity when 100 pg of genomic DNA was used. In addition, the absence of a SMN1 fragment at the 10-pg DNA level may be due to a PCR amplification failure, and, thus, it is difficult to interpret without a proper internal control. Our data indicate that PCR-RFLP can be used for most diagnostic purposes, whereas the use of allelespecific PCR may be considered with caution under certain circumstances.     

The cattle tick antigen, Bm95, expressed in Pichia pastoris contains short chains of N- and O-glycans

Bm95 is an antigen isolated from Boophilus microplus strains with low susceptibility to antibodies developed in cattle vaccinated with the recombinant Bm86 antigen (Gavac, HeberBiotec S.A., Cuba). It is a Bm86-like surface protein, which by similarity contains seven EGF-like domains and a lipid-binding GPI-anchor site at the C-terminal region. The primary structure of the recombinant (rBm95) protein expressed in Pichia pastoris was completely verified by LC/MS. The four potential glycosylation sites (Asn 122, 163, 329, and 363) are glycosylated partially with short N-glycans, from Man(5)GlcNAc(2) to Man(9)GlcNAc(2) of which, Man(8-9)GlcNAc(2) were the most abundant. O-Glycopeptides are distributed mostly towards the protein N-terminus. While the first N-glycosylated site (Asn(122)) is located between EGF-like domains 2 and 3, where the O-glycopeptides were found, two other N-glycosylated sites (Asn(329) and Asn(363)) are located between EGF-like domains 5 and 6, a region devoid of O-glycosylated Ser or Thr.     

Gain of allelic gene expression for IGF-II occurs frequently in Barrett's esophagus

The IGF-II gene normally exhibits genomic imprinting, a DNA modification that allows the expression of only one of the two inherited alleles. With loss of imprinting, there is a gain of allelic gene expression (GOAGE) due to IGF-II being expressed by both alleles. GOAGE for IGF-II has been demonstrated in a number of malignancies and in normal epithelia surrounding malignancies, but not in epithelia without associated neoplasia. We hypothesized that nonneoplastic Barrett's epithelium might have GOAGE for IGF-II that could facilitate its progression to neoplasia. Endoscopic biopsies were obtained from metaplastic esophageal, normal gastric, and normal duodenal epithelia from 43 patients with Barrett's esophagus. Genomic DNA were analyzed using PCR followed by ApaI restriction enzyme digestion or allele-specific PCR to identify an ApaI polymorphism of IGF-II. cDNA from patients with the ApaI polymorphism were analyzed for IGF-II GOAGE using exon connection PCR, followed by a secondary nested PCR and ApaI restriction enzyme digestion. We found that 13 (30%) of 43 samples of Barrett's metaplasia contained the ApaI polymorphism and were thus informative for IGF-II, and sufficient material was available for GOAGE analysis in 9 of those 13 cases. GOAGE for IGF-II was demonstrated in five (56%) of those nine cases. All patients with GOAGE in Barrett's metaplasia also demonstrated GOAGE in the gastric and duodenal epithelia. In contrast, patients without GOAGE in Barrett's metaplasia also had no GOAGE in their gastric and duodenal epithelia. We conclude that in patients with Barrett's esophagus, GOAGE for IGF-II is found frequently in the metaplastic esophageal epithelium as well as in normal gastric and duodenal epithelia.     

MDR1 Ala893 polymorphism is associated with inflammatory bowel disease

Crohn disease (CD) and ulcerative colitis (UC) are overlapping chronic inflammatory bowel diseases (IBDs). Suggestive evidence for linkage at chromosome 7q has been reported for both CD and UC. Contained within this region is the gene for MDR1 (multidrug resistance), a membrane transport protein for which human polymorphisms have been reported in Ala893Ser/Thr and C3435T that alter pharmacokinetic profiles for a variety of drugs. Because mdr1 knockout mice spontaneously develop colitis, exonic regions were resequenced and tested for IBD association in a large, multicenter North American cohort. Two missense mutations, Asn21Asp and Ala893Ser/Thr, as well as the expression-associated polymorphism C3435T, described elsewhere, were genotyped in the entire cohort. Significant association of Ala893 with IBD was observed by both case-control analysis (P=.002) and the pedigree disequilibrium test (PDT [P=.00020-.00030]) but not for the Asn21Asp or C3435T polymorphisms. Significant association by PDT was observed within the subset with CD (P=.0014-.00090), with similar, nonsignificant trends in a smaller subset with UC. The Ala893Ser/Thr variant is triallelic, and the associated, common allele is Ala893, with undertransmission of the 893Ser (common) and the 893Thr (rare) variants. The Ala893 variant has decreased activity compared with the 893Ser variant; therefore, the association with human IBD is consistent with the murine model of mdr1 deficiency. Taken together, these data support the association of the common Ala893 polymorphism with IBD specifically and, more broadly, provides additional support for its contribution to interindividual pharmacogenetic variation.     

A novel polymorphism of apolipoprotein A-IV is the result of an asparagine to serine substitution at residue 127

We have identified a hitherto genetic polymorphism of apolipoprotein A-IV (apo-IV). The molecular basis for this polymorphism is an A to G substitution at nucleotide 1687 resulting in an Asn to Ser change of amino acid 127. The frequencies of the two apoA-IV alleles (designated apoA-IV^127Asn and apoA-IV^127Ser), determined by Hinc II restriction analysis of PCR amplified exon three of the apoA-IV gene, were 0.788 and 0.212, respectively, in a Finnish population sample. Allele frequencies of another polymorphism due to a Thr to Ser substitution at amino acid 347 were determined using Hinf I restriction analysis. The allele frequencies were 0.823 for apoA-IV^347Thr and 0.177 for apoA-IV^247Ser. None of the apoA-IV polymorphisms (apoA-IV_{127:Asn→Ser}, apoA-IV_{347:Thr→Ser} and apoA-IV_{360:Gln→His}) had any effect of plasma lipid and lipoprotein concentrations in cohorts of dyslipidemic men and in a population sample of normolipidemic controls. There was also no association between the history of previous myocardial infarction and any of the apoA-IV alleles.