SYMPOSIA

Poster Presentations
and Spaniards.
One hundred and twenty-two (70 previously analyzed) white Spanish and 101 Mexican Mestizo patients with a diagnosis of MDD (DSM-
IV) were studied. Additionally, 327 Spaniards and 153 Mexican Mestizo healthy volunteers were also studied by a previously reported PCR
method [1]. Genotypes and allele frequencies were compared between MDD patients and HVs by two-tailed Fisher’s test.
The frequencies of 5HTTLPR LL, LS and SS genotypes in the Spanish population (MDD vs. HV) were 19.7 vs. 28.8%, 54.9 vs. 50.5% and 25.4
vs. 19.9 %. In the Mexican Mestizo population the frequencies in the MDD vs. HV groups were 14.9 vs. 18.3%, 49.5 vs. 55.6%, and 35.6 vs.
26.1% for 5HTTLPR LL, LS, and SS genotypes, respectively. The frequencies of 5-HTTLPR genotypes of the four groups (MDD and HV from
Spain and Mexico) corresponded to those predicted by the Hardy–Weinberg law.
The odds ratio associated with the 5-HTTLPR-S allele were 1.72 (95% CI: 1.04-2.85) and 1.28 (95% CI: 0.64-2.55) for the MDD in comparison
with the HV group in Spaniards and Mexicans, respectively.
The frequency of S was higher than the frequency of L allele in both MDD groups. In the Spanish population, the S allele was significantly
higher (p