Congenital Diarrhea and Cholestatic Liver Disease: Phenotypic Spectrum Associated with MYO5B Mutations

• Main Authors: Denise Aldrian, Georg F. Vogel, Teresa K. Frey, Hasret Ayyıldız Civan, Aysel Ünlüsoy Aksu, Yaron Avitzur, Ester Boluda Ramos, Murat Çakır, Arzu Meltem Demir, Caroline Deppisch, Hans-Christoph Duba, Gesche Düker, Patrick Gerner, Jozef Hertecant, Jarmila Hornová, Simone Kathemann, Jutta Koeglmeier, Arsinoi Koutroumpa, Roland Lanzersdorfer, Raffi Lev-Tzion, Rosa Lima, Sahar Mansour, Manfred Meissl, Jan Melek, Mohamad Miqdady, Jorge Hernan Montoya, Carsten Posovszky, Yelena Rachman, Tania Siahanidou, Merit Tabbers, Holm H. Uhlig, Sevim Ünal, Stefan Wirth, Frank M. Ruemmele, Michael W. Hess, Lukas A. Huber, Thomas Müller, Ekkehard Sturm, Andreas R. Janecke
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Journal of Clinical Medicine
• Subjects: congenital diarrheal diseases; enteropathy; microvillus inclusion disease; MYO5B; myosin Vb; progressive familial intrahepatic cholestasis
• Online Access: https://www.mdpi.com/2077-0383/10/3/481

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.