부산대학교 도서관

CONTEXT:: Pituitary blastoma causing Cushingʼs syndrome in infancy is very rare, and its molecular pathomechanism is not well understood. OBJECTIVE:: Our objective was to identify genetic changes of a pituitary blastoma causing infantile-onset Cushingʼs syndrome in a Thai girl without a family history of cancers. METHODS:: Genomic DNA from both leukocytes and tumor tissues was used for whole-exome sequencing (WES) and Sanger sequencing of DICER1. The cDNA reverse-transcribed from RNA extracted from both leukocytes and tumor tissues was used for Sanger sequencing, quantitative real-time PCR (qRT-PCR), and pyrosequencing of DICER1. RESULTS:: WES of leukocytes identified a novel heterozygous c.3046delA (p.S1016VfsX1065) mutation in the DICER1 gene. WES of the tumor tissues detected the same frameshift germline mutation and another novel somatic missense c.5438A→T (p.E1813V) mutation. Both mutations were validated by Sanger sequencing. Quantitative real-time PCR revealed that the DICER1 mRNA levels of the tumor tissues were 54% compared with those of her leukocytes. Pyrosequencing showed that the deletion allele constituted 12% and 0% of the DICER1 cDNA of the probandʼs leukocytes and tumor tissues, respectively. CONCLUSION:: Our study extends the phenotypic and mutational spectrum of DICER1 mutations to include infantile-onset Cushingʼs disease and 2 novel mutations. Loss of function of both DICER1 alleles appears to be crucial to initiate tumor development.