Serotonin transporter gene polymorphic element 5-HTTLPR increases the risk of sporadic Parkinson's disease in Italy

Parkinson's disease (PD) is a neurodegenerative disorder causing muscular rigidity, resting tremor and bradykinesia. We conducted an association study assessing how PD risk in Italy was influenced by the serotonin transporter gene (SLC6A4) polymorphic region 5-HTTLPR, consisting of an insertion/deletion (long allele-L/short allele-S) of 43 bp in the SLC6A4 promoter region. The SLC6A4 promoter single nucleotide polymorphism rs25531(A→G) was evaluated too. We collected 837 independent subjects (393 PD, 444 controls). An association between the 5-HTTLPR polymorphism and risk of PD (S/S genotype OR [95% CI]: 1.7[1.2-2.5], p = 0.002) was found. The rs25531 and the haplotype 5-HTTLPR/rs25531 did not associate with risk of PD. Our data indicate that the 5-HTTLPR polymorphic element within the SLC6A4 promoter may govern the genetic risk of PD in Italians.