Analysis of the disease risk locus DXS1047 polymorphism in Brazilian Alzheimer patients.

Alzheimer's disease (AD) is a disorder characterized by a progressive deterioration in memory and other cognitive functions. Four genes associated with early onset AD have been identified but familial AD is rare. The majority of late onset AD (LOAD) is caused by a complex inheritance with several genes interacting with environmental factors. The epsilon4 allele of the apolipoprotein E (APOE) gene has been reported worldwide as a risk factor associated with LOAD. The short variant of a polymorphism in the transcriptional region of the serotonin transporter gene (5-HTTLPR) was analyzed in several psychiatric conditions and found to be more frequently associated with European and Brazilian LOAD patients. Recently, allelic associations with LOAD were reported for five other loci, the most significant for one X-linked 202-bp allele, at the DXS1047 locus. We have analyzed this locus in Brazilian LOAD patients and observed that the 202-bp allele was not significantly more frequent among patients. In contrast, two other alleles (200 bp and 208 bp) were less frequent among AD male patients than in controls, confirming the importance of replicating association studies in different populations.