A novel allele in the promoter region of the human serotonin transporter gene

The human serotonin transporter (hSERT) gene is a promising candidate for mediating the genetic susceptibility for various psychiatric conditions such as mood 1 and obsessive-compulsive disorders. 2 Two polymorphic sites in this gene attracted much interest: a VNTR of 17-bp repeats in intron two, 3 and an insertion/deletion in the 5'-flanking promoter region (5-HTT gene-linked polymorphic region-5-HTTLPR) 4 creating a short (S) and a long (L) allele. The 5-HTTLPR polymorphism is situated in a GC-rich region composed of 20-23 bp repeating units. The S and L alleles have 14 and 16 repeat-elements respectively. Positive associations of the 5-HTTLPR polymorphism with mood disorders, 5 anxiety-related personality traits, 6 autism 7 and late-onset Alzheimer's 8 disease have been published, although some non replications were also reported. 9,10 Here we report a novel allele (termed LJ) in the 5-HTTLPR site. This allele is longer than the L allele by 43 bp, has 18 repeat units and contains two copies of the insertion/deletion sequence arranged in tandem. The LJ allele was found in individuals of Libyan and Tunisian Jewish origin but not in Moroccan or Ashkenazi Jews.