Comprehensive epidemiological and genotype–phenotype analyses in a large European sample with idiopathic achalasia

BACKGROUND AND AIMAlthough an eight-residue insertion in HLA-DQβ1 has been recently identified as a genetic risk factor for idiopathic achalasia, other risk factors are still unknown. In the present study, we carried out an epidemiological survey and a genotype–phenotype (G×P) analysis to gain further insights into the etiology of achalasia. METHODSWe obtained medical data from 696 achalasia patients and 410 controls, as well as their first-degree relatives (2543 of patients and 1497 of controls). For the G×P analysis, we stratified the patients into HLA-DQβ1 insertion carriers and noncarriers. RESULTSOur data show that patients are more often affected by viral infections before achalasia onset (P