An Pediatr (Barc). 2017;87(3):125---127 www.analesdepediatria.org EDITORIAL Genetic predisposition to childhood cancer  Predisposición genética al cáncer infantil Pilar Carrasco Salas a , Pablo Lapunzina b , Antonio Pérez-Martínez a,b,* a Laboratorio de Oncohematología Pediátrica Molecular, Instituto de Genética Médica y Molecular (INGEMM), Hospital Universitario La Paz, Madrid, Spain b Servicio de Hemato-Oncología Pediátrica, Hospital Infantil Universitario La Paz, Madrid, Spain Introduction In developing countries, childhood cancer is the leading cause of death due to illness in the paediatric age group. Its incidence has been growing continuously since the 1950s 1 due to advances in diagnostic tools and cancer registers, which has been associated with considerable improvements in prognosis and survival. However, the cure of childhood cancer seems to have met a therapeutic ceiling, plateauing at 70% in the past few decades. 2 We currently know that childhood cancer is a disease of multifactorial aetiology whose genetic basis is not entirely understood, with considerable involvement of the immune system and modulated by exposure to environmental fac- tors. At present, preventive measures are ineffective against childhood cancer. However, the detection of hereditary sus- ceptibility could be very relevant to patients and families. In some cases, it could lead to the implementation of  Please cite this article as: Carrasco Salas P, Lapunzina P, Pérez- Martínez A. Predisposición genética al cáncer infantil. An Pediatr (Barc). 2017;87:125---127. * Corresponding author. E-mail address: aperezmartinez@salud.madrid.org (A. Pérez-Martínez). preventive measures for the early detection of malignan- cies, both in the index case and in blood relatives. The genetics of cancer Cancer results from the accumulation of different genetic changes in a cell, sometimes over several years. These changes lead to abnormal cell proliferation and clonal expansion, which can ultimately invade other tissues. In most cases, genetic changes that promote tumori- genesis occur in somatic cells and do not involve germline mutations. Numerous genes involved in tumour development have been identified, and are classified into 3 different cat- egories: tumour-suppressor genes, proto-oncogenes and genes involved in genome stability. Tumour-suppressor genes control cell proliferation, inhibiting the progression of the cell cycle or inducing apoptosis (Fig. 1). Usually, a single functional copy of the gene suffices to carry out its func- tion. The inactivation of both alleles allows uncontrolled proliferation and thus contributes to tumour development. Conversely, proto-oncogenes promote cell proliferation and contribute to tumour progression when they are perma- nently activated as a result of mutations. In this case, mutations in a single allele suffice to produce uncontrolled proliferation. Genes involved in DNA stability do not play a direct role in the regulation of cell proliferation, but dys- function in these genes contributes to an increased number 2341-2879/© 2017 Asociaci´ on Espa˜ nola de Pediatr´ ıa. Published by Elsevier Espa˜ na, S.L.U. All rights reserved.