No abstract

We performed a linkage analysis in the total NIMH sample to assess the roles gender, education, and APOE e4 dose play in influencing the linkage to age at onset (AAO) of Alzheimer's disease. Treating AAO as a censored quantitative trait, we obtained the covariate-adjusted deviance residuals in Cox proportional hazard models and then analyzed the residuals as the quantitative trait in variance component linkage analyses in SOLAR. Adjusting for no covariates or gender produced identical heritability estimates of 7% and two peaks with LOD>1 on chromosome 5 at 68cM (LOD ¼ 1.16) and on chromosome 19 at 74cM (LOD ¼ 2.02). Adjusting for education alone or education plus gender not only increased the heritability to 22% but also detected three additional chromosome regions with LOD>1 on chromosome 2 at 283 cM (LOD ¼ 1.62), chromosome 7 at 50cM (LOD ¼ 1.78), and chromosome 9 at 133cM (LOD ¼ 1.32). However, adjusting for APOE e4 dose or APOE e4 dose plus gender resulted in the LOD scores below 1 in all 22 autosomes and lowered the heritability estimate to 4%. Our results suggested that gender had only minimal impact on the linkage to AAO; education had considerable influence but was not hypothesized to be causally related to AAO of AD; the APOE gene was more likely to be an intermediate in the causal pathway between other quantitative trait loci (QTL) and AAO. Our study also indicated that important environmental risk factors that decrease phenotypic variability through their adjustments should be included in the covariate linkage models, whereas effect modifiers that are causal or intermediate factors should not. 522-SA PILOT STUDY OF RAPID HIV TESTING AND COUNSELING SERVICE (CBVCT) FOR COMMERCIAL SEX VENUES IN LIMA, PERU. *S Sanchez, A Ghee, S Sanchez, M Jiménez, P Campos, F Spielberg (Asociacion Impacta Salud y Educacion, Lima, Peru) Female sexual workers (FSW) and their male clients play a crucial role in HIV transmission. New strategies, such as improved access to HIV counseling and testing (VCT), are central to HIV control efforts in these groups. An estimated 33% of FSW were screened in clinic settings in Metropolitan Lima in 2002. We studied the feasibility of mobile community-based VCT services (CBVCT) for FSW and their clients at commercial sex venues in the city of Lima. Self-identified FSW and clients !18 years old were invited to participate. Pretest counseling and rapid HIV testing were offered. Instead of giving rapid test results on-site, participants could obtain results and posttest counseling by telephone or in-person at a clinic site. Between November '05 and January '06 243 FSW and 170 clients had been offered the service; 91% of FSW and 37% of clients participated. The primary reasons FSW refused to participate were having been screened in the last year (48%) and a lack of confidence in the rapid test technology (14%). Among male clients the primary reasons were insufficient time available (32%) and seeing HIV testing as unnecessary because they were healthy (13%). Clients refused participation more ...