Since we did not include healthy age-matched controls, we cannot state with certainty that loss of SERT occurred in any of our patient groups, but loss of SERT in PD has been shown before with 11C‐3‐amino‐4‐(2‐dimethylaminomethylphenylsulfanyl)‐benzonitrile (11C-DASB), a SERT-selective positron emission tomography tracer (Politis et al., 2010). The gene discussed is SLC6A4; the disease is Parkinson disease.