Causes of pyloric atresia

Saw et al.1 refer to two reports of familial pyloric atresia; another example was recently reported by Keramidas and Voyatzis.2 Saw and co-authors state that 30 cases of pyloric atresia have been reported in the literature; Keramidas and Voyatzis mention a report in the German literature3 that "refers to 47 reported cases, and adds two reports." Another rare cause of nonbilious emesis is pyloric duplication, which may more closely mimic pyloric stenosis.4 Saw et al. bring up the "vascular" theory, i.e., intrauterine ischemic infarction, to explain pyloric atresia but I questioti5 whether this theory can be used to explain either pyloric atresia, pyloric duplicalions, or gastric duplications.