RESUMEN
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.
RESUMEN
Pediatric myocarditis is a common pediatric illness most commonly secondary to a preceding viral infection. It is a leading cause of acquired heart failure, cardiomyopathy, and cardiac transplantation in pediatrics. Due to the variability in presentation, the diagnosis is often unrecognized until later in the disease course. It should be considered in the differential diagnosis of all children presenting with respiratory distress, since this is the most common presentation. Imagining modalities, such as cardiac magnetic resonance imaging have become a useful diagnostic tool in recent years; however, endomyocardial biopsy remains the gold standard diagnostic test. Treatment of viral myocarditis is mainly supportive, with debatable role of anti-inflammatory, immunosuppressing immunomodulators and anti-viral therapy. Although, the outcome is generally favorable, delay in supportive care may be associated with a worse prognosis. We focus on the clinical presentation, review diagnostic and treatment options of viral myocarditis.