A Novel Study and Meta-Analysis of the Genetic Variation of the Serotonin Transporter Promoter in the Italian Population Do Not Support a Large Effect on Alzheimer's Disease Risk

Table 1

Literature overview of the 5-HTTLPR polymorphism in association with AD in the Caucasian population.

Reference	Population	No. of cases	No. of controls	Main result
[13]	UK	196	271	No association
[14]	Germany	84	118	No association
[15]	Germany	50	199	Association of S-allele with AD (S-allele frequency in AD and controls: 51% and 41%, resp.)
[16]	Italy	208	116	No association
[17]	Italy	105	114	No association
[18]	Austria	127	479	No association
[19]	Italy	164	54	Association of S-allele with AD
				(S-allele frequency in AD and controls: 47% and 34%, resp.)
This study (no overlapping with the above-cited populations)	Italy	220	197	Association of S-allele with AD (S-allele frequency in AD and controls: 47.5% and 40.1%, resp.)

AD: sporadic Alzheimer’s disease.