Ten years of <i>DICER1</i> mutations: Provenance, distribution, and associated phenotypes

DICER1 syndrome is a pleiotropic tumor predisposition syndrome characterized by a distinctive constellation of neoplastic and dysplastic lesions, which are generally rare and affect children and young adults. Germline pathogenic variants in the DICER1 gene are the underlying cause of the syndrome; variants are typically inherited in an autosomal dominant pattern but may arise de novo in the germline or in a somatic mosaic distribution. The encoded DICER1 protein is a key component of the microRNA processing pathway. In this Mutation Update, we present a comprehensive review of all DICER1 genetic alterations reported in articles published before January 31st, 2019. A total of 1,136 DICER1 alterations were catalogued from 808 individuals and the tumors that occurred in these persons. We provide an inventory of these DICER1 alterations and discuss them with respect to their provenance, distribution across the gene, associated phenotypes and ages of onset, and penetrance. We also address approaches to classification of DICER1 variants of uncertain significance and discuss the clinical significance of DICER1 variant identification.