5-HTTLPR, or Solute carrier family 6 (neurotransmitter transporter), member 4, is a human gene encoded by SLC6A4. It may also be known as: Sodium-dependent serotonin transporter; 5HTT; Solute carrier family 6 member 4; 5HT transporter; serotonin transporter 1; 5-HTT; OCD1; SERT; SERT1; hSERT. The encoded protein has an amino acid length of 630 and a mass of 70.3 kDa. Other isoforms may exist. 5-HTTLPR is a member of the Sodium:neurotransmitter symporter (SNF) (TC 2.A.22) family, SLC6A4 subfamily. Homologs of this gene exist in other organisms, including: Fly, Frog.