Mutation of FOXL2 in granulosa-cell tumors of the ovary

Background Granulosa-cell tumors (GCTs) are the most common type of malignant ovarian sex cord–stromal tumor (SCST). The pathogenesis of these tumors is unknown. Moreover, their histopathological diagnosis can be challenging, and there is no curative treatment beyond surgery. Methods We analyzed four adult-type GCTs using whole-transcriptome paired-end RNA sequencing. We identified putative GCT-specific mutations that were present in at least three of these samples but were absent from the transcriptomes of 11 epithelial ovarian tumors, published human genomes, and databases of single-nucleotide polymorphisms. We confirmed these variants by direct sequencing of complementary DNA and genomic DNA. We then analyzed additional tumors and matched normal genomic DNA, using a combination of direct sequencing, analyses of restriction-fragment–length polymorphisms, and TaqMan assays. Results All four index GCTs had a missense point mutation, 402C→G (C134W), in FOXL2, a gene encoding a transcription factor known to...