%0 Case Reports
%T Extraskeletal chondroma of the toe in a child with DICER1 tumor predisposition syndrome: support for a dominant negative mechanism.
%A Pelletier D
%A Sabbaghian N
%A Chong AL
%A Priest JR
%A Elsheikh Ahmed Y
%A Fox GP
%A Fabian MR
%A Foulkes WD
%J Virchows Arch
%V 484
%N 6
%D 2024 Jun 14
%M 38355738
%F 4.535
%R 10.1007/s00428-024-03759-y
%X DICER1 tumor predisposition syndrome is a pleiotropic disorder that gives rise to various mainly pediatric-onset lesions. We report an extraskeletal chondroma (EC) of the great toe occurring in a child who, unusually, carries a germline "hotspot" missense DICER1 variant rather than the more usual loss-of-function (LOF) variant. No heterozygous LOF allele was identified in the EC. We demonstrate this variant impairs 5p cleavage of precursor-miRNA (pre-miRNA) and competes with wild-type (WT) DICER1 protein for pre-miRNA processing. These results suggest a mechanism through which a germline RNase IIIb variant could impair pre-miRNA processing without complete LOF of the WT DICER1 allele.