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Myosin Vb (MYO5B) is a motor protein that facilitates protein trafficking and recycling in polarized cells by RAB11- and RAB8-dependent mechanisms. Biallelic MYO5B mutations are identified in the majority of patients with microvillus inclusion disease (MVID). MVID is an intractable diarrhea of infantile onset with characteristic histopathologic findings that requires life-long parenteral nutrition or intestinal transplantation. A large number of such patients eventually develop cholestatic liver disease. Bi-allelic MYO5B mutations are also identified in a subset of patients with predominant early-onset cholestatic liver disease. We present here the compilation of 114 patients with disease-causing MYO5B genotypes, including 44 novel patients as well as 35 novel MYO5B mutations, and an analysis of MYO5B mutations with regard to functional consequences. Our data support the concept that (1) a complete lack of MYO5B protein or early MYO5B truncation causes predominant intestinal disease (MYO5B-MVID), (2) the expression of full-length mutant MYO5B proteins with residual function causes predominant cholestatic liver disease (MYO5B-PFIC), and (3) the expression of mutant MYO5B proteins without residual function causes both intestinal and hepatic disease (MYO5B-MIXED). Genotype-phenotype data are deposited in the existing open MYO5B database in order to improve disease diagnosis, prognosis, and genetic counseling.

Background and AimsAn expanding number of monogenic defects have been identified as causative of severe forms of very early-onset inflammatory bowel diseases [VEO-IBD]. The present study aimed at defining how next-generation sequencing [NGS] methods can be used to improve identification of known molecular diagnosis and to adapt treatment.MethodsA total of 207 children were recruited in 45 paediatric centres through an international collaborative network [ESPGHAN GENIUS working group] with a clinical presentation of severe VEO-IBD [n = 185] or an anamnesis suggestive of a monogenic disorder [n = 22]. Patients were divided at inclusion into three phenotypic subsets: predominantly small bowel inflammation, colitis with perianal lesions, and colitis only. Methods to obtain molecular diagnosis included functional tests followed by specific Sanger sequencing, custom-made targeted NGS, and in selected cases whole exome sequencing [WES] of parents-child trios. Genetic findings were validated clinically and/or functionally.ResultsMolecular diagnosis was achieved in 66/207 children [32%]: 61% with small bowel inflammation, 39% with colitis and perianal lesions, and 18% with colitis only. Targeted NGS pinpointed gene mutations causative of atypical presentations, and identified large exonic copy number variations previously missed by WES.ConclusionsOur results lead us to propose an optimised diagnostic strategy to identify known monogenic causes of severe IBD.

Background: Treatment quality and outcomes of paediatric home parenteral nutrition (HPN) program during its development in the Czech Republic. Methods: A retrospective study of patients receiving HPN from May 1995 till June 2011. Results: Sixty-six patients were treated in 8 centres. In 48 patients, long-term PN began in the first year of life and in 35 of them in the first month. Sixty children had gastrointestinal and 6 had non-gastrointestinal disease. In a majority of the patients, the Broviac catheter was used. Thirty-two (48.5%) patients were weaned from PN after 1-117 months, 21 (32.8%) continued on HPN after 7-183 months, and 13 (19.7%) patients died, all on PN. The mortality in patients with primary gastrointestinal disease was significantly lower than in patients with non-gastrointestinal disease. Thirty-one paediatric patients were receiving HPN for 14,480 catheter days in 2009-2010. Fourteen patients had 23 Catheter Related Blood Stream Infections (CRBSI) episodes. The incidence of CRBSI in 2009-2010 was 1.58/1,000 catheter days. Conclusion: Submitted data showed that even in the absence of expert centres, patient care may achieve results comparable to countries with well-developed HPN program. A majority of Czech HPN patients are at present treated in specialized centres, following the most desirable pattern of care.