“…In this context, the identification of the anatomical site of gut (mega‐esophagus, ‐stomach, ‐duodenum, small bowel, ‐colon, ‐rectum) or urinary tract (mega‐ureter, ‐bladder) dilatation, such as megaduodenum in Mungan's syndrome 88 or urinary tract dilatation in enteric smooth muscle actin gamma 2 (ACTG2) gene mutations, 89 may help to identify the phenotype. In addition, the concurrent presence of some alterations of esophageal manometry, such as the ineffective or absent contractility in the esophageal body have been found to be associated with ACTG2 mutations affecting smooth muscle function, 20,90 and direct sequencing is recommended in such cases 20 . Since the number of phenotypes associated with specific genetic mutations is increasing, genetic testing with parallel massive sequencing, either targeting a pool of selected candidate genes or the whole‐exome, is also encouraged when the clinical diagnosis is uncertain.…”