title: Relation between apolipoprotein E genotype, hepatitis B virus status, and thyroid status in a sample of older persons with Down syndrome.
abstract: Dementia of the Alzheimer type (DAT) is common in older persons with Down syndrome (DS). There are three common alleles of the apolipoprotein E (ApoE) gene (Sigma 2, Sigma 3, and Sigma 4) resulting in three different isoforms (E2, E3, and E4) and six different genotypes (2,2; 2,3; 2,4; 3,3; 3,4; and 4,4). Sigma 4 is a risk factor for DAT whereas Sigma 2 appears prophylactic. As hepatitis B virus (HBV) infection and hypothyroidism also are common in DS, we evaluated associations between ApoE type, HBV status, and thyroid status in a sample of older persons with DS (n = 55; mean age, 44.3 +/- 10.8 years) using chi-squared analysis. Participants were classified as E2 (2,2 or 2,3), E3 (3,3), or E4 (3,4 or 4,4); positive for markers of HBV infection in the present or past (i.e., total HBcAb+ and/or HBsAg+ with or without infectivity, defined as HBV+) or negative for markers of HBV infection (defined as HBV-) and, currently receiving thyroid hormone supplement (defined as "hypothyroidism") or having normal thyroid function. The majority of the HBV+ were currently HBcAb+ and HBsAb+, but not HBsAg+. In females, there was an ApoE allele effect on thyroid status (P < or = 0.01), E2 being negatively (P < or = 0.01) and E4 being positively (P < or = 0.05) associated with "hypothyroidism". There was no evidence for an ApoE allele effect on thyroid status in males. There was no evidence for an ApoE allele effect on HBV status, or for an HBV status effect on thyroid status. As thyroid status can affect cognitive function, ApoE allele effects in DAT may, in part, be thyroid effects.
authors.affiliation: Department of Physiology, University of Toronto, Toronto, Ontario, Canada. maire.percy@utoronto.ca
authors.forename: Maire E
authors.initials: ME
authors.lastname: Percy
authors.forename: Zoya
authors.initials: Z
authors.lastname: Potyomkina
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Dalton
authors.forename: Bettye
authors.initials: B
authors.lastname: Fedor
authors.forename: Pankaj
authors.initials: P
authors.lastname: Mehta
authors.forename: David F
authors.initials: DF
authors.lastname: Andrews
authors.forename: Tony
authors.initials: T
authors.lastname: Mazzulli
authors.forename: Lillian
authors.initials: L
authors.lastname: Murk
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Warren
authors.forename: Robyn A
authors.initials: RA
authors.lastname: Wallace
authors.forename: Hien
authors.initials: H
authors.lastname: Chau
authors.forename: Winnie
authors.initials: W
authors.lastname: Jeng
authors.forename: Sharon
authors.initials: S
authors.lastname: Moalem
authors.forename: Lisa
authors.initials: L
authors.lastname: O'Brien
authors.forename: Sonia
authors.initials: S
authors.lastname: Schellenberger
authors.forename: Helen
authors.initials: H
authors.lastname: Tran
authors.forename: Linda
authors.initials: L
authors.lastname: Wu
mesh_terms: D000328:Adult; D001057:Apolipoproteins E / Q000235:genetics*; D004314:Down Syndrome / Q000150:complications* / Q000235:genetics*; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000150:complications*; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000276:immunology; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000235:genetics; D012737:Sex Factors; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood
chemical_list: D001057:Apolipoproteins E; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D020033:Protein Isoforms; D013972:Thyrotropin