**Author details**

José Maldonado

Unit of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Virgen de las Nieves University Hospital, University of Granada, Spain

\*Address all correspondence to: jmaldon@ugr.es

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
