A research group from Spain analyzed the associations of three polymorphisms in the dopamine genes (D2 receptor: Taq1A; D3 receptor: Ser9Gly; and dopamine transporter: DAT1 variable number of tandem repeats) with binge eating symptoms in patients with BED (n = 34) or BN (n = 80) [60]. This evidence concerns the gene SLC6A3 and X-linked cone dysfunction syndrome with myopia.