David D. Hebrink

Association of APOE polymorphisms with disease severity in MS is limited to women

The authors studied the association of an exon 4 (E4*ε2/3/4) and three promoter polymorphisms of APOE with disease course and severity stratified by gender in 221 patients with multiple sclerosis from two overlapping population-based prevalence cohorts. Women carriers of the E4*ε2 allele took longer to attain an Expanded Disability Status Scale score of 6 (p = 0.015) and had more favorable ranked severity scores than noncarriers (p = 0.009). There was no association in men. Alleles ε3 or ε4 and promoter polymorphisms were not associated with disease course or severity.

Association of two variants in IL-1β and IL-1 receptor antagonist genes with multiple sclerosis

We studied the putative association of a C-->T polymorphism in exon-5 of IL-1beta and an 85 bp tandem repeat in intron-4 of IL-1 receptor antagonist (IL-1ra) genes with susceptibility to or outcome of MS. DNA from 122 cases from a population-based cohort in Olmsted County, MN who were previously categorized for disease severity and temporal course and 244 ethnically-matched controls were analyzed. There was no association between either polymorphism and disease susceptibility. Allele-2 of IL-1beta and allele-3 of the IL-1ra polymorphisms were associated with a favorable outcome (P=0.023 and P=0.030).

IFNG polymorphisms are associated with gender differences in susceptibility to multiple sclerosis

Interferon-gamma (IFNγ) treatment is deleterious in multiple sclerosis (MS). MS occurs twice as frequently in women as in men. IFNγ expression varies by gender. We studied a population-based sample of US MS patients and ethnicity-matched controls and independent Northern Irish and Belgian hospital-based patients and controls for association with MS, stratified by gender, of an intron 1 microsatellite [I1(761)*CAn], a single nucleotide polymorphism 3′ of IFNG [3′(325)*G → A] and three flanking microsatellite markers spanning a 118 kb region around IFNG. Men carriers of the 3′(325)*A allele have increased susceptibility to MS compared to noncarriers in the USA (P=0.044; OR: 2.58, 95% CI: 0.97–8.08) and Northern Ireland (P=0.019; OR: 2.37, 95% CI: 1.10–5.13). There is a nonsignificant trend in the same direction in Belgian men (P=0.299; OR: 1.50, 95% CI: 0.71–3.26). Men carriers of I1(761)*CA13, which is in strong linkage disequilibrium with the 3′(325)*A, have increased susceptibility (P=0.050; OR: 2.22, 95% CI: 0.98–5.40), while men carriers of I1(761)*CA12 have decreased susceptibility (P=0.022; OR: 0.46, 95% CI: 0.23–0.90) to MS in the USA. Similar associations were reported in Sardinia between the I1(761)*CA12 allele and reduced risk of MS in men. Flanking markers were not associated with MS susceptibility. Polymorphisms of IFNG may contribute to differences in susceptibility to MS between men and women.

Myeloperoxidase -463 (G→A) polymorphism associated with lower risk of lung cancer

OBJECTIVE To study the association of the myeloperoxidase (MPO) -463 (G-->A) polymorphism with lung cancer risk. PATIENTS AND METHODS We performed a paired case-control analysis of 307 patients with primary lung cancer and an equal number of age-, sex-, and ethnicity-matched controls to evaluate the effect of the MPO -463 (G-->4A) polymorphism on disease susceptibility. We also performed conditional logistic regression analyses to evaluate the effect of the polymorphism adjusted for smoking status and chronic obstructive pulmonary disease, 2 established risk factors. We used 2 models for these analyses: one to compare homozygous (AA) genotypes with wild type (GG) and heterozygous (GA) genotypes and one to compare carriers (heterozygotes and AA homozygotes) with GG genotypes. Finally, we combined the results from the published studies of this putative association and performed a stratified analysis. RESULTS The AA genotype was inversely associated with susceptibility to lung cancer (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.15-1.00). There was no association in heterozygotes. However, in the stratified analysis, we found an association between patients with the AA (OR, 0.44; 95% CI, 0.27-0.68) and GA (OR, 0.77; 95% CI, 0.64-0.93) genotypes vs the GG genotype. CONCLUSION Our results are consistent with previous reports and show that homozygotes of the less common A allele of MPO -463 polymorphism have a 2.6-fold lower risk of lung cancer.

Genetic analysis of aquaporin-4 in neuromyelitis optica.

Objective: Autoantibodies to aquaporin-4 (AQP4) are specific and pathogenic for neuromyelitis optica (NMO). Therefore, we evaluated whether AQP4 single-nucleotide polymorphisms (SNPs) are associated with susceptibility to NMO or whether mutations that potentially alter AQP4 structure or expression are present in some patients. Methods: We genotyped 8 AQP4 SNPs chosen based on their minor allele frequency, location, and novelty in 177 NMO sporadic cases, 14 NMO familial cases, and 1,363 matched controls by TaqMan-based assay. We performed bidirectional sequencing of the promoter (1 kb), exons 0–4, and flanking splice consensus sequences, and the 5′ and 3′ untranslated regions of 177 sporadic and 14 familial NMO cases. Results: One of 8 SNPs (minor allele frequency = 0.01) was associated with NMO (NC 18.8; chrom pos. 22695167: T>A): odds ratio (95% confidence interval) = 13.1 (1.4–126.7); p = 0.026. In 3 patients with NMO (2 related), we detected 2 different missense allelic mutations at Arg19 (R19I and R19T). None of the 1,363 control subjects had Arg19 mutations (p = 0.001). Conclusions: Except for one uncommon SNP, no tested SNP was associated with NMO, nor were 3 SNP haplotypes, providing no support for the hypothesis that genetic variation in AQP4 accounts for overall susceptibility to NMO. Two different allelic Arg19 missense mutations are specific to NMO and segregated with the disease in one pedigree. Although the pathobiology underlying this is not yet established, their effects on the structure of the M1 isoform N terminus or the regulatory sequence of the M23 isoform by virtue of their location support a role of AQP4 orthogonal array formation on molecular susceptibility to NMO.

Association of a myeloperoxidase promoter polymorphism with multiple sclerosis

Myeloperoxidase (MPO) generates hypochlorous acid and other reactive oxygen intermediates leading to tissue damage. MPO is expressed in macrophages-microglia in multiple sclerosis (MS) lesions. A G-->A substitution that abolishes an SP1 transcription factor consensus sequence in the promoter reduces gene expression. We studied the association of the genetic variant with MS. We did not find an association with gender, age at onset, susceptibility to, or the course and severity of MS in a population-based sample of 122 patients from Olmsted County.

Interferon gamma allelic variants: sex-biased multiple sclerosis susceptibility and gene expression.

BACKGROUND Interferon (IFN) gamma (IFNG) allelic variants are associated with susceptibility to multiple sclerosis (MS) in men but not in women. OBJECTIVES To conduct a high-density linkage disequilibrium association study of IFNG and the surrounding region for sex-associated MS susceptibility bias and to evaluate whether IFNG allelic variants associated with MS susceptibility are associated with expression. DESIGN Genotype case-control study, quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay expression analyses for IFN gamma. SETTING Three independently ascertained populations from the Mayo Clinic, Rochester, Minnesota, Queens University of Belfast, Belfast, Ireland, and University of Leuven, Leuven, Belgium. PATIENTS For linkage disequilibrium, 861 patients with MS (293 men and 568 women) and 843 controls (340 men and 503 women) derived from the US (population-based) and the Northern Ireland and Belgium (clinic-based) cohorts were studied. For expression analyses, 50 US patients were selected to enrich for homozygotes and to achieve a balance between men and women. INTERVENTIONS Twenty markers were genotyped over the 120-kilobase region harboring IFNG and the interleukin 26 gene (IL26). MAIN OUTCOME MEASURES Expression of IFN gamma was evaluated by qPCR and enzyme-linked immunosorbent assay in stimulated peripheral blood mononuclear cells. RESULTS Multiple markers were associated with MS susceptibility in men but not in women. The sex-specific susceptibility markers, of which rs2069727 was the strongest, were confined to IFNG. Carriers of rs2069727*G had higher expression than noncarriers. The effect of genotype in the qPCR experiments was also evident in men but not in women. CONCLUSIONS IFNG is associated with sex bias in MS susceptibility and with expression of IFN gamma in MS. These observations add to a growing body of literature that implicates an interaction between sex and IFN gamma expression in a variety of disease states.

Screening the monoamine oxidase B gene in 100 male patients with schizophrenia: A cluster of polymorphisms in African‐Americans but lack of functionally significant sequence changes

The monoamine oxidase B (MAO-B) gene was examined in 100 alleles derived from 80 Caucasian, 10 African-American, 5 Asian, and 5 Native American male patients with schizophrenia to identify sequence changes that might be associated with the disease. Approximately 235 kb of genomic sequence, primarily in coding regions, were screened by dideoxy fingerprinting, a modification of single-strand conformational polymorphism (SSCP) analysis that detects virtually 100% of sequence changes [Sarkar et al. (1992): Genomics 13:441-443; Liu and Sommer (1994): PCR Methods Appl 4:97-108]. No sequence changes of likely functional significance were identified, suggesting that mutations affecting the structure of the MAO-B protein are uncommon in the general population and are unlikely to contribute significantly to the genetic predisposition to schizophrenia. Eight polymorphisms were identified in African-Americans and Native Americans, but none were identified among Caucasians. Of the eight observed polymorphisms, a set of five transitions and one microdeletion was identified within approximately 17 kb of genomic sequence in the same 3 African-American individuals, while the remaining 7 African-Americans had a sequence identical to that in Caucasians. The presence of two such haplotypes, without intermediates, is compatible with the hypothesis that germline mutations can occur in clusters, as also suggested by other recent findings.

Genetic variants in the tumor necrosis factor receptor 1 gene in patients with MS.

Article abstract We scanned for all genetic variants in functionally important regions of the tumor necrosis factor receptor 1 gene (TNF-R1) in 100 to 111 MS patients from Olmsted County, MN, and analyzed selected variants for an association with disease course and severity. Ten genetic variants were uncovered. Only one variant, a silent substitution, was found in coding sequence. One intronic variant may generate a novel splice-junction sequence. We did not find an association between either this intronic variant or another common promoter variant and the course or severity of MS.

Genetic variation in the transforming growth factor β1 gene in multiple sclerosis

Transforming growth factor beta1 (TGFbeta1) is a Th2 cytokine encoded on chromosome 19q13, a region possibly linked to multiple sclerosis (MS). TGFbeta1 exerts favorable effects on experimental allergic encephalomyelitis. We performed a comprehensive search for genetic variants in this gene in 122 population-based sporadic cases of MS. We detected six variants, including three missense variants. We tested for association of the variants with susceptibility and course of MS and for linkage and transmission disequilibrium in a family series consisting of 395 samples in 59 pedigrees. Genetic variation in TGFB1 does not appear to contribute in a major way to susceptibility to MS.