Background/Purpose: Patients with zinc finger homeo box 1B (ZFHX1B) mutations or deletions develop multiple congenital anomalies including Hirschsprung disease, known as Mowat-Wilson syndrome (MWS). In this study, we investigated variations in the enteric neural plexus abnormalities in MWS using morphometry-based histopathologic analysis. Methods: Seven patients with MWS (3 with mutations in exon 8 of ZFHX1B and 4 with deletions) who had undergone modified Duhamel’ s operations for Hirschsprung disease were examined. Surgically resected rectosigmoid specimens were analyzed morphometrically. Results: The length of the aganglionic segment was longer than 3 cm in all the patients with deletions. In 3 patients with mutations, the aganglionic region was not detected in the surgically resected specimens; however, the parameters of the ganglions and plexus were significantly smaller than those of controls (cloaca and aproctia), indicative of a transitional zone. Variation in the severity of pathological changes among the 3 patients with mutations was also noted. Conclusions: The variations in myenteric plexus pathologies in MWS appear to be caused by both variations in ZFHX1B abnormalities and epigenetic factors. Background / Purpose: Patients with zinc finger home box 1B (ZFHX1B) mutations or deletions develop multiple congenital anomalies including Hirschsprung disease, known as Mowat-Wilson syndrome (MWS). In this study, we morph variations in the enteric neural plexus abnormalities in MWS Using morphometry-based histopathologic analysis. Methods: Seven patients with MWS (3 with mutations in exon 8 of ZFHX1B and 4 with deletions) who had undergone modified Duhamel ’s operations for Hirschsprung disease were examined. Surgically resected rectosigmoid specimens were morphologically morph. : The length of the aganglionic segment was longer than 3 cm in all the patients with deletions. In 3 patients with mutations, the aganglionic region was not detected in the surgically resected specimens; however, the parameters of the ganglions and plexus were significantly smaller than those of controls (cloaca and aproctia), indicative of a transitional zone. Variation in the severity of p athological changes among the 3 patients with mutations was also noted. Conclusions: The variations in myenteric plexus pathologies in MWS appear to be caused by both variations in ZFHX1B abnormalities and epigenetic factors.