Mitchell-Riley Syndrome : Improving Clinical Outcomes and Searching for Functional Impact of RFX-6 Mutations

Aims/HypothesisCaused by biallelic mutations of the gene encoding the transcription factor RFX6, the rare Mitchell-Riley syndrome (MRS) comprises neonatal diabetes, pancreatic hypoplasia, gallbladder agenesis or hypoplasia, duodenal atresia, and severe chronic diarrhea. So far, sixteen cases have been reported, all with a poor prognosis. This study discusses the multidisciplinary intensive clinical management of 4 new cases of MRS that survived over the first 2 years of life. Moreover, it demonstrates how the mutations impair the RFX6 function. MethodsClinical records were analyzed and described in detail. The functional impact of two RFX6(R181W) and RFX6(V506G) variants was assessed by measuring their ability to transactivate insulin transcription and genes that encode the L-type calcium channels required for normal pancreatic beta-cell function. ResultsAll four patients were small for gestational age (SGA) and prenatally diagnosed with duodenal atresia. They presented with neonatal diabetes early in life and were treated with intravenous insulin therapy before switching to subcutaneous insulin pump therapy. All patients faced recurrent hypoglycemic episodes, exacerbated when parenteral nutrition (PN) was disconnected. A sensor-augmented insulin pump therapy with a predictive low-glucose suspension system was installed with good results. One patient had a homozygous c.1517T>G (p.Val506Gly) mutation, two patients had a homozygous p.Arg181Trp mutation, and one patient presented with new compound heterozygosity. The RFX6(V506G) and RFX6(R181W) mutations failed to transactivate the expression of insulin and genes that encode L-type calcium channel subunits required for normal pancreatic beta-cell function. Conclusions/InterpretationMultidisciplinary and intensive disease management improved the clinical outcomes in four patients with MRS, including adjustment of parenteral/oral nutrition progression and advanced diabetes technologies. A better understanding of RFX6 function, in both intestine and pancreas cells, may break ground in new therapies, particularly regarding the use of drugs that modulate the enteroendocrine system.Peer reviewe

Results of an International Survey on Feeding Management in Infants With Short Bowel Syndrome-Associated Intestinal Failure

Objectives: Short bowel syndrome (SBS) is a complex and rare condition (incidence 1200/100,000 live births) that requires a multidisciplinary team approach to management. In January 2019, the first European Reference Network on Rare and Inherited Congenital Anomalies (ERNICA) Intestinal Failure (IF) workshop was held. Several questions about the strategies used in managing IF associated with SBS were devised. The aim of our study was to collect data on the enteral feeding strategies adopted by the ERNICA centres. Methods: A questionnaire (36 questions) about strategies used to introduce enteral nutrition post-operatively and start complementary food/solids in infants with SBS associated IF was developed and sent to 24 centres in 15 countries that participated in the ERNICA-IF workshop. The answers were collated and compared with the literature. Results: There was a 100% response rate. In infants, enteral nutrition was introduced as soon as possible, ideally within 24–48 hours post-small intestinal surgical resection. In 10 of 24 centres, bolus feeding was used, in nine continuous, and in five a combination of both. Twenty-three centres used mothers’ own milk as the first choice of feed with extensively hydrolysed feed, amino acid-based feed, donor human milk or standard preterm/term formula as the second choice. Although 22 centres introduced complementary/solid food by 6 months of age, food choice varied greatly between centres and appeared to be culturally based. Conclusions: There is diversity in post-surgical enteral feeding strategies among centres in Europe. Further multi-centre studies could help to increase evidence-based medicine and management on this topic