John MacMillan

Griffith University, Brisbane, Queensland, Australia

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Publications (13)25.06 Total impact

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    Article: The effects of vitamin supplementation and MTHFR (C677T) genotype on homocysteine-lowering and migraine disability.
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    ABSTRACT: Migraine is a prevalent and debilitating disease that may, in part, arise because of disruption in neurovascular endothelia caused by elevated homocysteine. This study examined the homocysteine-lowering effects of vitamin supplementation on migraine disability, frequency and severity and whether MTHFRC677T genotype influenced treatment response. This was a randomized, double-blind placebo, controlled trial of 6 months of daily vitamin supplementation (i.e. 2 mg of folic acid, 25 mg vitamin B6, and 400 microg of vitamin B12) in 52 patients diagnosed with migraine with aura. Vitamin supplementation reduced homocysteine by 39% (approximately 4 mumol/l) compared with baseline, a reduction that was greater then placebo (P=0.001). Vitamin supplementation also reduced the prevalence of migraine disability from 60% at baseline to 30% after 6 months (P=0.01), whereas no reduction was observed for the placebo group (P>0.1). Headache frequency and pain severity were also reduced (P<0.05), whereas there was no reduction in the placebo group (P>0.1). In this patient group the treatment effect on both homocysteine levels and migraine disability was associated with MTHFRC677T genotype whereby carriers of the C allele experienced a greater response compared with TT genotypes (P<0.05). This study provides some early evidence that lowering homocysteine through vitamin supplementation reduces migraine disability in a subgroup of patients. Larger trials are now warranted to establish whether vitamin therapy is a safe, inexpensive and effective prophylactic option for treatment of migraine and whether efficacy is dependant on MTHFRC677T genotype.
    Pharmacogenetics and Genomics 05/2009; 19(6):422-8. · 3.48 Impact Factor
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    Article: Investigation of the NOTCH3 and TNFSF7 genes on C19p13 as candidates for migraine.
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    ABSTRACT: To investigate the migraine locus around the C19p13 region through analysis of the NOTCH3 gene (C19p13.2-p13.1), previously shown to be a gene involved in CADASIL and the TNFSF7 gene (C19p13), homologous to the ligands of TNF-alpha and TNF-beta, genes that have previously been associated with migraine. The NOTCH3 gene was analysed by sequencing all exons with known CADASIL mutations in a typical (non-familial hemiplegic) migraine family (MF1) that has previously been shown to be linked to C19p13. The TNFSF7 gene was investigated through SNP association analysis using a matched case-control migraine population. NOTCH3 gene sequencing results for affected members of MF1 proved to be negative for all known sequence variants giving rise to mutations for CADASIL. TNFSF7 gene chi-square results showed non-significant P values across all populations tested against controls, except for the MO subgroup which displayed a possible association with the TNFSF7 SNP (genotype, allele analysis P = 0.036, P = 0.017 respectively). Our results suggest that common migraine is not caused by any known CADASIL mutations in the NOTCH3 gene of interest. However, the TNFSF7 gene displayed signs of involvement in a MO affected population and indicates that further independent studies of this marker are warranted.
    The Open Neurology Journal 02/2008; 2:1-7.
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    Article: Association analysis of chromosome 1 migraine candidate genes.
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    ABSTRACT: Migraine with aura (MA) is a subtype of typical migraine. Migraine with aura (MA) also encompasses a rare severe subtype Familial Hemiplegic Migraine (FHM) with several known genetic loci. The type 2 FHM (FHM-2) susceptibility locus maps to chromosome 1q23 and mutations in the ATP1A2 gene at this site have recently been implicated. We have previously provided evidence of linkage of typical migraine (predominantly MA) to microsatellite markers on chromosome 1, in the 1q31 and 1q23 regions. In this study, we have undertaken a large genomic investigation involving candidate genes that lie within the chromosome 1q23 and 1q31 regions using an association analysis approach. We have genotyped a large population of case-controls (243 unrelated Caucasian migraineurs versus 243 controls) examining a set of 5 single nucleotide polymorphisms (SNPs) and the Fas Ligand dinucleotide repeat marker, located within the chromosome 1q23 and 1q31 regions. Several genes have been studied including membrane protein (ATP 1 subtype A4 and FasL), cytoplasmic glycoprotein (CASQ 1) genes and potassium (KCN J9 and KCN J10) and calcium (CACNA1E) channel genes in 243 migraineurs (including 85% MA and 15% of migraine without aura (MO)) and 243 matched controls. After correction for multiple testing, chi-square results showed non-significant P values (P > 0.008) across all SNPs (and a CA repeat) tested in these different genes, however results with the KCN J10 marker gave interesting results (P = 0.02) that may be worth exploring further in other populations. These results do not show a significant role for the tested candidate gene variants and also do not support the hypothesis that a common chromosome 1 defective gene influences both FHM and the more common forms of migraine.
    BMC Medical Genetics 01/2007; 8:57. · 2.33 Impact Factor
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    Article: Association analysis of a highly polymorphic CAG Repeat in the human potassium channel gene KCNN3 and migraine susceptibility.
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    ABSTRACT: Migraine is a polygenic multifactorial disease, possessing environmental and genetic causative factors with multiple involved genes. Mutations in various ion channel genes are responsible for a number of neurological disorders. KCNN3 is a neuronal small conductance calcium-activated potassium channel gene that contains two polyglutamine tracts, encoded by polymorphic CAG repeats in the gene. This gene plays a critical role in determining the firing pattern of neurons and acts to regulate intracellular calcium channels. The present association study tested whether length variations in the second (more 3') polymorphic CAG repeat in exon 1 of the KCNN3 gene, are involved in susceptibility to migraine with and without aura (MA and MO). In total 423 DNA samples from unrelated individuals, of which 202 consisted of migraine patients and 221 non-migraine controls, were genotyped and analysed using a fluorescence labelled primer set on an ABI310 Genetic Analyzer. Allele frequencies were calculated from observed genotype counts for the KCNN3 polymorphism. Analysis was performed using standard contingency table analysis, incorporating the chi-squared test of independence and CLUMP analysis. Overall, there was no convincing evidence that KCNN3 CAG lengths differ between Caucasian migraineurs and controls, with no significant difference in the allelic length distribution of CAG repeats between the population groups (P = 0.090). Also the MA and MO subtypes did not differ significantly between control allelic distributions (P > 0.05). The prevalence of the long CAG repeat (>19 repeats) did not reach statistical significance in migraineurs (P = 0.15), nor was there a significant difference between the MA and MO subgroups observed compared to controls (P = 0.46 and P = 0.09, respectively), or between MA vs MO (P = 0.40). This association study provides no evidence that length variations of the second polyglutamine array in the N-terminus of the KCNN3 channel exert an effect in the pathogenesis of migraine.
    BMC Medical Genetics 10/2005; 6:32. · 2.33 Impact Factor
  • Article: Genetic variants of angiotensin converting enzyme and methylenetetrahydrofolate reductase may act in combination to increase migraine susceptibility.
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    ABSTRACT: Migraine, with and without aura (MA and MO), is a prevalent and complex neurovascular disorder that is likely to be influenced by multiple genes some of which may be capable of causing vascular changes leading to disease onset. This study was conducted to determine whether the ACE I/D gene variant is involved in migraine risk and whether this variant might act in combination with the previously implicated MTHFR C677T genetic variant in 270 migraine cases and 270 matched controls. Statistical analysis of the ACE I/D variant indicated no significant difference in allele or genotype frequencies (P > 0.05). However, grouping of genotypes showed a modest, yet significant, over-representation of the DD/ID genotype in the migraine group (88%) compared to controls (81%) (OR of 1.64, 95% CI: 1.00-2.69, P = 0.048). Multivariate analysis, including genotype data for the MTHFR C677T, provided evidence that the MTHFR (TT) and ACE (ID/DD) genotypes act in combination to increase migraine susceptibility (OR = 2.18, 95% CI: 1.15-4.16, P = 0.018). This effect was greatest for the MA subtype where the genotype combination corresponded to an OR of 2.89 (95% CI:1.47-5.72, P = 0.002). In Caucasians, the ACE D allele confers a weak independent risk to migraine susceptibility and also appears to act in combination with the C677T variant in the MTHFR gene to confer a stronger influence on the disease.
    Molecular Brain Research 06/2005; 136(1-2):112-7. · 2.00 Impact Factor
  • Article: Investigation of hormone receptor genes in migraine.
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    ABSTRACT: Migraine is a common neurological condition with a complex mode of inheritance. Steroid hormones have long been implicated in migraine, although their role remains unclear. Our investigation considered that genes involved in hormonal pathways may play a role in migraine susceptibility. We therefore investigated the androgen receptor (AR) CAG repeat, and the progesterone receptor (PR) PROGINS insert by cross-sectional association analysis. The results showed no association with the AR CAG repeat in our study group of 275 migraineurs and 275 unrelated controls. Results of the PR PROGINS analysis showed a significant difference in the same cohort, and in an independent follow-up study population of 300 migraineurs and 300 unrelated controls. Analysis of the genotypic risk groups of both populations together indicated that individuals who carried the PROGINS insert were 1.8 times more likely to suffer migraine. Interaction analysis of the PROGINS variant with our previously reported associated ESR1 594A variant showed that individuals who possessed at least one copy of both risk alleles were 3.2 times more likely to suffer migraine. Hence, variants of these steroid hormone receptor genes appear to act synergistically to increase the risk of migraine by a factor of three.
    Neurogenetics 03/2005; 6(1):17-23. · 3.35 Impact Factor
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    Article: The estrogen receptor 1 G594A polymorphism is associated with migraine susceptibility in two independent case/control groups.
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    ABSTRACT: Migraine is a painful and debilitating disorder with a significant genetic component. Steroid hormones, in particular estrogen, have long been considered to play a role in migraine, as variations in hormone levels are associated with migraine onset in many sufferers of the disorder. Steroid hormones mediate their activity via hormone receptors, which have a wide tissue distribution. Estrogen receptors have been localized to the brain in regions considered to be involved in migraine pathogenesis. Hence it is possible that genetic variation in the estrogen receptor gene may play a role in migraine susceptibility. This study thus examined the estrogen receptor 1 (ESRalpha) gene for a potential role in migraine pathogenesis and susceptibility. A population-based cohort of 224 migraine sufferers and 224 matched controls were genotyped for the G594A polymorphism located in exon 8 of the ESR1 gene. Statistical analysis indicated a significant difference between migraineurs and non-migraineurs in both the allele frequencies (P=0.003) and genotype distributions (P=0.008) in this sample. An independent follow-up study was then undertaken using this marker in an additional population-based cohort of 260 migraine sufferers and 260 matched controls. This resulted in a significant association between the two groups with regard to allele frequencies (P=8 x 10(-6)) and genotype distributions (P=4 x 10(-5)). Our findings support the hypothesis that genetic variation in hormone receptors, in particular the ESR1 gene, may play a role in migraine.
    Neurogenetics 07/2004; 5(2):129-33. · 3.35 Impact Factor
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    Article: The methylenetetrahydrofolate reductase gene variant C677T influences susceptibility to migraine with aura.
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    ABSTRACT: The C677T variant in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with increased levels of circulating homocysteine and is a mild risk factor for vascular disease. Migraine, with and without aura (MA and MO), is a prevalent and complex neurovascular disorder that may also be affected by genetically influenced hyperhomocysteinaemia. To determine whether the C677T variant in the MTHFR gene is associated with migraine susceptibility we utilised unrelated and family-based case-control study designs. A total of 652 Caucasian migraine cases were investigated in this study. The MTHFR C677T variant was genotyped in 270 unrelated migraine cases and 270 controls as well as 382 affected subjects from 92 multiplex pedigrees. In the unrelated case-control sample we observed an over-representation of the 677T allele in migraine patients compared to controls, specifically for the MA subtype (40% vs. 33%) (chi2 = 5.70, P = 0.017). The Armitage test for trend indicated a significant dosage effect of the risk allele (T) for MA (chi2 = 5.72, P = 0.017). This linear trend was also present in the independent family-based sample (chi2 = 4.25, Padjusted = 0.039). Overall, our results indicate that the T/T genotype confers a modest, yet significant, increase in risk for the MA subtype (odds ratio: 2.0 - 2.5). No increased risk for the MO subtype was observed (P > 0.05). In Caucasians, the C677T variant in the MTHFR gene influences susceptibility to MA, but not MO. Investigation into the enzyme activity of MTHFR and the role of homocysteine in the pathophysiology of migraine is warranted.
    BMC Medicine 02/2004; 2:3. · 6.03 Impact Factor
  • Article: No mutations detected in the INSR gene in a chromosome 19p13 linked migraine pedigree.
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    ABSTRACT: The aim of this study was to investigate through direct sequencing the insulin receptor (INSR) gene in DNA samples from a migraine affected family previously showing linkage to chromosome 19p13 in an attempt to detect disease associated mutations. Migraine is a common debilitating disorder with a significant genetic component. At present, the number and type of genes involved in the common forms of migraine are not clear. The INSR gene on chromosome 19p13.3-13.2 is a gene of interest since a number of single nucleotide polymorphisms (SNPs) located within the gene have been implicated in migraine with (MA) and without aura (MO). Six DNA samples obtained from non-founding migraine affected members of migraine family 1 (MF1) were used in this study. Genomic DNA was sequenced for the INSR gene in exons 1-22 and the promoter region. In the six migraine family member samples, previously reported SNPs were detected within two exonic DNA coding regions of the INSR gene. These SNPs, in exons 13 and 17, do not alter the normal INSR polypeptide sequence. In addition, intron 7 also revealed a DNA base sequence variation. For the 5' untranslated promoter region of the gene, no mutations or polymorphisms were detected. In conclusion, this study detected no INSR mutations in affected members of a chromosome 19 linked migraine pedigree. Hence, migraine linkage to this chromosomal region may involve other candidate genes.
    European Journal of Medical Genetics 49(1):57-62. · 2.18 Impact Factor
  • Article: The effects of vitamin supplementation and MTHFR (C677T) genotype on homocysteine-lowering and migraine disability
    [show abstract] [hide abstract]
    ABSTRACT: Yes Yes
  • Article: Association analysis of a highly polymorphic CAG Repeat in the human potassium channel gene KCNN3 and migraine susceptibility.
    [show abstract] [hide abstract]
    ABSTRACT: Background Migraine is a polygenic multifactorial disease, possessing environmental and genetic causative factors with multiple involved genes. Mutations in various ion channel genes are responsible for a number of neurological disorders. KCNN3 is a neuronal small conductance calcium-activated potassium channel gene that contains two polyglutamine tracts, encoded by polymorphic CAG repeats in the gene. This gene plays a critical role in determining the firing pattern of neurons and acts to regulate intracellular calcium channels. Methods The present association study tested whether length variations in the second (more 3') polymorphic CAG repeat in exon 1 of the KCNN3 gene, are involved in susceptibility to migraine with and without aura (MA and MO). In total 423 DNA samples from unrelated individuals, of which 202 consisted of migraine patients and 221 non-migraine controls, were genotyped and analysed using a fluorescence labelled primer set on an ABI310 Genetic Analyzer. Allele frequencies were calculated from observed genotype counts for the KCNN3 polymorphism. Analysis was performed using standard contingency table analysis, incorporating the chi-squared test of independence and CLUMP analysis. Results Overall, there was no convincing evidence that KCNN3 CAG lengths differ between Caucasian migraineurs and controls, with no significant difference in the allelic length distribution of CAG repeats between the population groups (P = 0.090). Also the MA and MO subtypes did not differ significantly between control allelic distributions (P > 0.05). The prevalence of the long CAG repeat (>19 repeats) did not reach statistical significance in migraineurs (P = 0.15), nor was there a significant difference between the MA and MO subgroups observed compared to controls (P = 0.46 and P = 0.09, respectively), or between MA vs MO (P = 0.40). Conclusion This association study provides no evidence that length variations of the second polyglutamine array in the N-terminus of the KCNN3 channel exert an effect in the pathogenesis of migraine. Page numbers are not for citation purposes. Instead, this article has the unique article number of 32. Yes Yes
  • Article: The methylenetetrahydofolate reductase gene variant C677T influences susceptibility to migraine with aura
    [show abstract] [hide abstract]
    ABSTRACT: Background The C677T variant in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with increased levels of circulating homocysteine and is a mild risk factor for vascular disease. Migraine, with and without aura (MA and MO), is a prevalent and complex neurovascular disorder that may also be affected by genetically influenced hyperhomocysteinaemia. To determine whether the C677T variant in the MTHFR gene is associated with migraine susceptibility we utilised unrelated and family-based case-control study designs. Methods A total of 652 Caucasian migraine cases were investigated in this study. The MTHFR C677T variant was genotyped in 270 unrelated migraine cases and 270 controls as well as 382 affected subjects from 92 multiplex pedigrees. Results In the unrelated case-control sample we observed an over-representation of the 677T allele in migraine patients compared to controls, specifically for the MA subtype (40% vs. 33%) (χ2 = 5.70, P = 0.017). The Armitage test for trend indicated a significant dosage effect of the risk allele (T) for MA (χ2 = 5.72, P = 0.017). This linear trend was also present in the independent family-based sample (χ2 = 4.25, Padjusted = 0.039). Overall, our results indicate that the T/T genotype confers a modest, yet significant, increase in risk for the MA subtype (odds ratio: 2.0 – 2.5). No increased risk for the MO subtype was observed (P > 0.05). Conclusions In Caucasians, the C677T variant in the MTHFR gene influences susceptibility to MA, but not MO. Investigation into the enzyme activity of MTHFR and the role of homocysteine in the pathophysiology of migraine is warranted. Page numbers are not for citation purposes. Instead, this article has the unique article number of 3. Yes Yes
  • Article: No mutations detected in the INSR gene in a chromosome 19p13 linked migraine pedigree
    [show abstract] [hide abstract]
    ABSTRACT: The aim of this study was to investigate through direct sequencing the insulin receptor (INSR) gene in DNA samples from a migraine affected family previously showing linkage to chromosome 19p13 in an attempt to detect disease associated mutations. Migraine is a common debilitating disorder with a significant genetic component. At present, the number and type of genes involved in the common forms of migraine are not clear. The INSR gene on chromosome 19p13.3–13.2 is a gene of interest since a number of single nucleotide polymorphisms (SNPs) located within the gene have been implicated in migraine with (MA) and without aura (MO). Six DNA samples obtained from non-founding migraine affected members of migraine family 1 (MF1) were used in this study. Genomic DNA was sequenced for the INSR gene in exons 1–22 and the promoter region. In the six migraine family member samples, previously reported SNPs were detected within two exonic DNA coding regions of the INSR gene. These SNPs, in exons 13 and 17, do not alter the normal INSR polypeptide sequence. In addition, intron 7 also revealed a DNA base sequence variation. For the 5′ untranslated promoter region of the gene, no mutations or polymorphisms were detected. In conclusion, this study detected no INSR mutations in affected members of a chromosome 19 linked migraine pedigree. Hence, migraine linkage to this chromosomal region may involve other candidate genes. Yes Yes