Hirschsprung disease (HSCR, aganglionic megacolon) is a frequent congenital malformation regarded as a multigenic neurocristopathy. Two susceptibility genes have been recently identified in HSCR, namely the RET proto-oncogene and the endothelin B receptor (EDNRB) gene. Hitherto however, homozygosity for EDNRB mutations accounted for the HSCR-Waardenburg syndrome (WS) association. Here, we report heterozygous EDNRB missense mutations (G57S, R319W and P383L) in isolated HSCR. These data might suggest that EDNRB mutations could be dosage sensitive: heterozygosity would predispose to isolated HSCR with incomplete penetrance, while homozygosity would result in more complex neurocristopathies associating HSCR and WS features. In addition, the present data give further support to the role of the endothelin-signalling pathway in the development of neural crest-derived enteric neurons.

The results emphasize that for successful implantation of an artificial urinary sphincter in children, the pre-operative bladder capacity must be sufficient and previous surgery should not have been performed on the bladder neck, the site of choice for implantation in children. Sphincterotomy is not always necessary in paediatric patients. Children and parents should be informed of the high complication rate and the need for long-term follow-up.

82 endoscopic surgical procedures (abdominal: 77; thoracic: 5) were performed by the same surgeon on 75 children aged from 1 month to 17 years (median 8.1 years) during the two-year period from January 1991 to December 1992. Due to the multispecialization of the Children's Hospital, a variety of pathologies were explored or treated with appendectomy accounting for 33% (27/82). There were no perioperative deaths. Three major complications occurred (1 post-appendectomy peritonitis, 1 hemorrhage during splenectomy and 1 post-operative occlusion). 14 patients required conversion to open surgery. Indications for endoscopic exploration of advanced lesions, prospective indications, and policy when confronted with a healthy appendix are discussed.

A large intraoperative tracheal tear occurred during correction of a type III esophageal atresia in a 1,630-g premature baby. It was repaired by primary suture. Recurrence of the tracheoesophageal fistula (TEF) was treated operatively with esophageal exclusion and costal cartilage grafting (CCG) onto the tracheal defect. At 3 months of age, successful esophageal reconstruction was performed using a posterior mediastinal colonic interposition. On 27-month follow-up, the child was symptom-free and thriving. Surgical options for TEF recurrence and intraoperative management of the tracheal air leak are discussed. CCG is advocated as an attractive material for tracheal repair even in low-weight prematures.