In these studies, the presence of an eight-residue insertion at position 227–234 of the cytoplasmic region of the HLA-DQβ1 chain (specifically encoded in DQB1*05:03 and DQB1*06:01 alleles) determines the susceptibility to achalasia; however, the mechanisms underlying this result are still poorly understood [9]. The gene discussed is HLA-DQB1; the disease is Achalasia.