Objective. To determine the diagnostic role of the MTNR1B expression by epitheliocytes of the distal esophagus in predicting obstructive sleep apnea/hypopnea syndrome among patients with gastroesophageal reflux disease.

Materials and methods. 84 patients aged 30—60 including those with gastroesophageal reflux disease (Group 1, n=25), patients with gastroesophageal reflux disease combined with obstructive apnea/hypopnea syndrome (Group 2, n=23), patients with obstructive apnea/hypopnea syndrome (Group 3, n=18) and patients lacking gastroesophageal reflux disease and obstructive sleep apnea/hypopnea syndrome included into the group of comparison (Group 4, n=18) were examined. The melatonin 1В receptors (MTNR1B) expression was evaluated by immunohistochemical method in the distal esophageal mucosa bioptates.

Results. The MTNR1B expression was increased in 52.2% (95% СI: 33.0—70.8) of Group 2 patients and in 4% (95% СI: < 0.01—21.1) of Group 1 patients (P=0.00001). The increased MTNR1B expression was associated with the sleep apnea severity (r=0.50; Р=0.0016). The MTNR1B expression threshold value equal to 0.176 was determined.

Conclusion. The determined level of the melatonin 1В receptors expression by epitheliocytes of the distal esophagus with 91.3% sensitivity and 78.3% specificity can be used to detect patients with gastroesophageal reflux disease requiring polysomnographic examinations.