{Reference Type}: Case Reports
{Title}: Extraskeletal chondroma of the toe in a child with DICER1 tumor predisposition syndrome: support for a dominant negative mechanism.
{Author}: Pelletier D;Sabbaghian N;Chong AL;Priest JR;Elsheikh Ahmed Y;Fox GP;Fabian MR;Foulkes WD;
{Journal}: Virchows Arch
{Volume}: 484
{Issue}: 6
{Year}: 2024 Jun 14
{Factor}: 4.535
{DOI}: 10.1007/s00428-024-03759-y
{Abstract}: 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.