Functional Analysis and Clinical Data Reclassify the DICER1 c.4206+1G>C Variant, Leading to Exon 22 Skipping, as Likely Pathogenic.

Pathogenic germline variants in DICER1 predispose to pleuropulmonary blastoma, multinodular goitre, embryonal rhabdomyosarcomas of the uterine cervix, ovarian Sertoli-Leydig cell tumour and a broader spectrum of pathologies. Here, we report a 35-year-old female with diagnoses of pineoblastoma, embryonal rhabdomyosarcoma, leiomyosarcoma, two meningiomas, and a germline DICER1 c.4206+1G>C, p.(?) variant. The variant was classified as a variant of unknown significance (VUS) based on the current ACMG/AMP gene-specific DICER1 guidelines. Additional functional analysis showed that the variant clearly abrogates the function of DICER1 and therefore PS3_Supporting evidence is included in the classification. Based on this the variant is reclassified as likely pathogenic. Moreover, our data suggest that the current ACMG/AMP gene-specific DICER1 guidelines should be modified in relation to the level of evidence strength (moderate to strong/very strong) for exon 22 skipping as well as to the use of the functional evidence (PS3) code.