Idiopathic achalasia is characterized by a failure of the lower esophageal sphincter to relax due to a loss of neurons in the myenteric plexus. This ultimately leads to massive dilatation and an irreversibly impaired megaesophagus. We performed a genetic association study in 1,068 achalasia cases and 4,242 controls and fine-mapped a strong MHC association signal by imputing classical HLA haplotypes and amino acid polymorphisms. An eight-residue insertion at position 227-234 in the cytoplasmic tail of HLA-DQβ1 (encoded by HLA-DQB1*05:03 and HLA-DQB1*06:01) confers the strongest risk for achalasia (P=1.73×10(-19)). In addition, two amino acid substitutions in the extracellular domain of HLA-DQα1 at position 41 (lysine encoded by HLA-DQA1*01:03; P=5.60×10(-10)) and of HLA-DQβ1 at position 45 (glutamic acid encoded by HLA-DQB1*03:01 and HLA-DQB1*03:04; P=1.20×10(-9)) independently confer achalasia risk. Our study implies that immune-mediated processes are involved in the pathophysiology of achalasia.

The range of normal pressure responses to a rapid drink challenge test in health has been established in a large multicenter study. Main responses are a virtually complete inhibition of esophageal pressures with a low-pressure gradient across esophagogastric junction. This data would allow the correct differentiation between normal and disease when using this test.

Background The definition and relevance of ineffective esophageal motility (IEM) remains debated. Our aim was to determine motility patterns and symptoms associated with IEM defined as impaired bolus clearance. Methods To define altered bolus clearance, normal range of swallows with complete bolus transit (CBT) on high‐resolution impedance manometry (HRIM) was determined in 44 asymptomatic controls. The results were then applied to a cohort of 81 patients with esophageal symptoms to determine the motility patterns which best predicted altered bolus clearance. Subsequently, in a cohort of 281 consecutive patients the identified motility patterns were compared with patients’ customary symptoms. Key Results In asymptomatic controls, the normal range of swallows with CBT was 50%‐100%. In patients, altered bolus transit (<50% CBT) was only associated with 30% or more failed contractions (P < .001). Neither weak peristalsis nor absence of contraction reserve (CR) was associated with altered bolus clearance. The patterns which best predicted altered bolus clearance were failed contractions ≥30% (specificity 88.2% and sensitivity of 84.6%), and ≥70% ineffective (failed + weak) contractions (sensitivity 84.6% and specificity 80.9%). No motility pattern was correlated to symptom scores. Conclusions and Inferences Based on bolus clearance assessed by HRIM, ≥30% failed contractions and ≥70% ineffective contractions have the best sensitivity and specificity to predict altered bolus clearance. Weak contractions and absence of CR are not relevant with respect to bolus clearance.

Idiopathic achalasia is a severe motility disorder of the esophagus and is characterized by a failure of the lower esophageal sphincter to relax due to a loss of neurons in the myenteric plexus. Most recently, we identified an eight-amino-acid insertion in the cytoplasmic tail of HLA-DQβ1 as strong achalasia risk factor in a sample set from Central Europe, Italy and Spain. Here, we tested whether the HLA-DQβ1 insertion also confers achalasia risk in the Polish and Swedish population. We could replicate the initial findings and the insertion shows strong achalasia association in both samples (Poland P = 1.84 × 10 − 04 , Sweden P = 7.44 × 10 − 05 ). Combining all five European data sets -Central Europe, Italy, Spain, Poland and Sweden -the insertion is achalasia associated with P combined = 1.67 × 10 − 35 . In addition, we observe that the frequency of the insertion shows a geospatial north-south gradient. The insertion is less common in northern (around 6-7% in patients and 2% in controls from Sweden and Poland) compared with southern Europeans (~16% in patients and 8% in controls from Italy) and shows a stronger attributable risk in the southern European population. Our study provides evidence that the prevalence of achalasia may differ between populations.

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