CONTEXT: Pituitary blastoma causing Cushing's 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 Cushing's 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 proband's leukocytes and tumor tissues, respectively. CONCLUSION: Our study extends the phenotypic and mutational spectrum of DICER1 mutations to include infantile-onset Cushing's disease and 2 novel mutations. Loss of function of both DICER1 alleles appears to be crucial to initiate tumor development.
CONTEXT: Pituitary blastoma causing Cushing's 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 Cushing's 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 proband's leukocytes and tumor tissues, respectively. CONCLUSION: Our study extends the phenotypic and mutational spectrum of DICER1 mutations to include infantile-onset Cushing's disease and 2 novel mutations. Loss of function of both DICER1 alleles appears to be crucial to initiate tumor development.
Authors: Anthony P Y Liu; Megan M Kelsey; Nelly Sabbaghian; Sung-Hye Park; Cheri L Deal; Adam J Esbenshade; Oswald Ploner; Andrew Peet; Heidi Traunecker; Yomna H E Ahmed; Margaret Zacharin; Anatoly Tiulpakov; Anastasia M Lapshina; Andrew W Walter; Pinaki Dutta; Ashutosh Rai; Márta Korbonits; Leanne de Kock; Kim E Nichols; William D Foulkes; John R Priest Journal: J Clin Endocrinol Metab Date: 2021-01-23 Impact factor: 5.958