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13 results on '"Tozer, D.J."'

4. Association of common genetic variants with brain microbleeds

Author

Knol, M.J., Lu, D.W., Traylor, M., Adams, H.H.H., Romero, J.R.J., Smith, A.V., Fornage, M., Hofer, E., Liu, J.F., Hostettler, I.C., Luciano, M., Trompet, S., Giese, A.K., Hilal, S., Akker, E.B. van den, Vojinovic, D., Li, S., Sigurdsson, S., Lee, S.J. van der, Jack, C.R., Wilson, D., Yilmaz, P., Satizabal, C.L., Liewald, D.C.M., Grond, J. van der, Chen, C., Saba, Y., Lugt, A. van der, Bastin, M.E., Windham, B.G., Cheng, C.Y., Pirpamer, L., Kantarci, K., Himali, J.J., Yang, Q., Morris, Z., Beiser, A.S., Tozer, D.J., Vernooij, M.W., Amin, N., Beekman, M., Koh, J.Y., Stott, D.J., Houlden, H., Schmidt, R., Gottesman, R.F., MacKinnon, A.D., DeCarli, C., Gudnason, V., Deary, I.J., Duijn, C.M. van, Slagboom, P.E., Wong, T.Y., Rost, N.S., Jukema, J.W., Mosley, T.H., Werring, D.J., Schmidt, H., Wardlaw, J.M., Ikram, M.A., Seshadri, S., Launer, L.J., Markus, H.S., Neurology, Amsterdam Neuroscience - Neurodegeneration, Epidemiology, Neurosciences, Clinical Genetics, and Radiology & Nuclear Medicine

Subjects
0301 basic medicine, medicine.medical_specialty, education.field_of_study, business.industry, Population, Genome-wide association study, Single-nucleotide polymorphism, Odds ratio, Gastroenterology, Hyperintensity, 03 medical and health sciences, 030104 developmental biology, 0302 clinical medicine, Internal medicine, Genetic predisposition, medicine, Neurology (clinical), Allele, business, education, 030217 neurology & neurosurgery, Genetic association
Abstract

ObjectiveTo identify common genetic variants associated with the presence of brain microbleeds (BMBs).MethodsWe performed genome-wide association studies in 11 population-based cohort studies and 3 case–control or case-only stroke cohorts. Genotypes were imputed to the Haplotype Reference Consortium or 1000 Genomes reference panel. BMBs were rated on susceptibility-weighted or T2*-weighted gradient echo MRI sequences, and further classified as lobar or mixed (including strictly deep and infratentorial, possibly with lobar BMB). In a subset, we assessed the effects of APOE ε2 and ε4 alleles on BMB counts. We also related previously identified cerebral small vessel disease variants to BMBs.ResultsBMBs were detected in 3,556 of the 25,862 participants, of which 2,179 were strictly lobar and 1,293 mixed. One locus in the APOE region reached genome-wide significance for its association with BMB (lead single nucleotide polymorphism rs769449; odds ratio [OR]any BMB [95% confidence interval (CI)] 1.33 [1.21–1.45]; p = 2.5 × 10−10). APOE ε4 alleles were associated with strictly lobar (OR [95% CI] 1.34 [1.19–1.50]; p = 1.0 × 10−6) but not with mixed BMB counts (OR [95% CI] 1.04 [0.86–1.25]; p = 0.68). APOE ε2 alleles did not show associations with BMB counts. Variants previously related to deep intracerebral hemorrhage and lacunar stroke, and a risk score of cerebral white matter hyperintensity variants, were associated with BMB.ConclusionsGenetic variants in the APOE region are associated with the presence of BMB, most likely due to the APOE ε4 allele count related to a higher number of strictly lobar BMBs. Genetic predisposition to small vessel disease confers risk of BMB, indicating genetic overlap with other cerebral small vessel disease markers.

Published
2020

10. Correlation of apparent myelin measures obtained in multiple sclerosis patients and controls from magnetization transfer and multicompartmental T2 analysis.

Author

Tozer, D.J., Davies, G.R., Altmann, D.R., Miller, D.H., and Tofts, P.S.

Abstract

Two relatively new techniques purport to give measures of the myelin content of brain tissue. These measures are the myelin water fraction from multicompartmental T2 analysis, and the semisolid proton fraction from analysis of magnetization transfer (MT). The myelin water fraction is the fraction of signal with a T2 of less than 50 ms measured from a 32-echo sequence. It is believed to originate from water trapped between the myelin bilayers. The semisolid proton fraction is thought to include protons within phospholipid bilayers and macromolecular protons, and may also be a measure of myelin content. Multicompartmental T2 and MT imaging were carried out on controls and patients with multiple sclerosis (MS), and estimates of the semisolid proton and myelin water fractions were obtained from white matter (WM), gray matter (GM), and MS lesions. These were then correlated for each tissue and subject group. Positive correlations were seen for MS lesions (r ≈ 0.2) and in WM in patients (r = 0.6). A negative correlation (r ≈ −0.3) was seen for GM. These results indicate that the two techniques measure, to some extent, the same thing (most likely myelin content), but that other factors, such as inflammation, mean they may provide complementary information. Magn Reson Med 53:1415-1422, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Published
2005
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