Association analysis of chromosome 1 migraine candidate genes

Background  

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.     

A typical migraine susceptibility region localizes to chromosome 1q31

Migraine (with and without aura) is a prevalent neurovascular disease that shows strong familial aggregation, although the number of genes involved and the mode of inheritance is not clear. Some insight into the disease has been gained from genetic studies into a rare and very severe migraine subtype known as familial hemiplegic migraine (FHM). In this study, we took a family-based linkage and association approach to investigate the FHM susceptibility region on chromosome 1q31 for involvement in typical migraine susceptibility in affected Australian pedigrees. Initial multipoint ALLEGRO analysis provided strong evidence for linkage of Chr1q31 markers to typical migraine in a large multigenerational pedigree. The 1-LOD* unit support interval for suggestive linkage spanned approximately 18 cM with a maximum allele sharing LOD* score of 3.36 obtained for marker D1S2782 (P=0.00004). Subsequent analysis of an independent sample of 82 affected pedigrees added support to the initial findings with a maximum LOD* of 1.24 (P=0.008). Utilising the independent sample of 82 pedigrees, we also performed a family-based association test. Results of this analysis indicated distortion of allele transmission at marker D1S249 [global χ² ₍₅₎ of 15.00, P=0.010] in these pedigrees. These positive linkage and association results will need further confirmation by independent researchers. However, overall they provide good evidence for the existence of a typical migraine locus near these markers on Chr1q31, and reinforce the idea that an FHM gene in this genomic region may also contribute to susceptibility to the more common forms of migraine. Electronic Publication     

Tissue-binding antibodies in tropical populations

A high, positive correlation was observed between IgM levels and human tissue complement fixing antibody in sera from normal New Guineans. The antibodies were of the IgM class as determined by immunofluorescence. In a small series of sera and tissues obtained post mortem, it was found that the sera reacted much more strongly with isologous than with autologous tissues. It was concluded that the antibodies were iso-antibodies, rather than auto-antibodies.     

Lipid composition and fluidity of the human immunodeficiency virus.

Lipid analyses of the human immunodeficiency virus (HIV) propagated in Hut 78 cells indicated a low total lipid/protein ratio, a high cholesterol/phospholipid molar ratio, and major phospholipids consisting of phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and phosphatidylserine; comparable lipid profiles were noted for human erythrocytes and other RNA viruses. Electron spin resonance (ESR) studies of HIV labeled with 5-nitroxide stearate (N-oxy-4',4'-dimethyloxazolidine derivative of ketostearate) showed a low "fluidity" at 37 degrees C, similar to other enveloped RNA viruses and erythrocytes and probably due to the high cholesterol/phospholipid ratio. Ethanol (50%) completely disrupts the envelope, contributing to the rapid inactivation of HIV by ethanol. Contrarily, heating to 57 degrees C causes much less fluidization, and this heating may play a role in the slower viral inactivation at high temperatures. Should a critical minimum ordering in the HIV envelope be necessary for viral stability and infectivity, manipulating the lipid composition or fluidizing the HIV membrane, or both, may provide an untried therapeutic approach.     

Anti-I Agglutinins in Non-Human Sera

Summary. Macroglobulin cold haemagglutinins, mostly of anti-I specificity, were found in high incidence and titre in sera from sheep, cattle, kangaroos, wallabies, wombats and possums living in a range of environments in Australia. There was neither positive nor negative correlation between the I-antigen content of the cells of the different species and the incidence of cold haemagglutinins. For example, the red cells of laboratory rabbits were still capable of binding radioactively labelled I-antibody at 37°C, yet the rabbit sera had the weakest cold haemagglutinins in the lowest incidence.
It is suggested that these results pointed to a widespread heteroantigen as the aetiological agent involved in the production of anti-I cold haemagglutinins in animals and man. The configuration of the I-antigen rather than that of the I-antibody is probably altered by cooling so that it more closely resembles the heteroantigen. Thus anti-I cold haemagglutinins would not be true autoantibodies since I does not exist at physiological temperatures in most species.
The occurrence in sheep and cattle sera of higher titres of cold haemagglutinins after reinfection with Ostertagia and Trichostrongylus suggests that further studies should be carried out on the possible role of metazoan parasites as aetiological agents in the production of cold haemagglutinins.     

No mutations detected in the INSR gene in a chromosome 19p13 linked migraine pedigree

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.     

Impact of residential medication management reviews on anticholinergic burden in aged care residents

Objectives:

The primary objective of this study was to investigate the impact of Residential Medication Management Reviews (RMMRs) on anticholinergic burden quantified by seven anticholinergic risk scales.

Design:

Retrospective analysis.

Setting:

Accredited pharmacists conducted RMMRs in aged-care facilities (ACFs) in Sydney, Australia.

Participants:

RMMRs pertained to 814 residents aged 65 years or older.

Measurements:

Anticholinergic burden was quantified using seven scales at baseline, after pharmacists’ recommendations and after the actual GP uptake of pharmacists’ recommendations. Change in the anticholinergic burden was measured using the Wilcoxon sign rank test.

Results:

At baseline, depending on the scale used to estimate the anticholinergic burden, between 36% and 67% of patients were prescribed at least one regular anticholinergic medication (ACM). Anticholinergic burden scores were significantly (p?<?0.001) lower after pharmacists’ recommendations as determined by each of the seven scales. The reduction in anticholinergic burden was also significant (p?<?0.001) after GPs’ acceptance of the pharmacists’ recommendations according to all scales with the exception of one scale which reached borderline significance (p?=?0.052).

Conclusion:

Despite the limitations of the retrospective design and differences in the estimation of anticholinergic burden, this is the first study to demonstrate that RMMRs are effective in reducing ACM prescribing in ACF residents, using a range of measures of anticholinergic burden. Future studies should focus on whether a decrease in anticholinergic burden will translate into improvement in clinical outcomes.     

Minor head trauma-induced sporadic hemiplegic migraine coma

Familial hemiplegic migraine is a severe, rare subtype of migraine. Gene mutations on chromosome 19 have been identified in the calcium channel, voltage-dependent, P/Q type, alpha-1A subunit gene (chromosome 19p13) for familial hemiplegic migraine. Recently a gene mutation (Serine-218-Leucine) for a dramatic syndrome associated with familial hemiplegic migraine, commonly named "migraine coma", has implicated exon 5 of this gene. The occurrence of trivial head trauma, in such familial hemiplegic migraine patients, may also be complicated by severe, sometimes even fatal, cerebral edema and coma occurring after a lucid interval. Sporadic hemiplegic migraine shares a similar spectrum of clinical presentation and genetic heterogeneity. The case report presented in this article implicates the involvement of the Serine-218-Leucine mutation in the extremely rare disorder of minor head trauma-induced migraine coma. We conclude that the Serine-218-Leucine mutation in the calcium channel, voltage-dependent, P/Q type, alpha-1A subunit gene is involved in sporadic hemiplegic migraine, delayed cerebral edema and coma after minor head trauma.