Germline-Somatic Interplay Shapes Molecular Divergence in Peripheral Nerve Sheath Tumors.

NF1

Germline NF1 variant followed by somatic biallelic inactivation, most often by loss of heterozygosity, then co-alterations of CDKN2A, SUZ12, EED or TP53 in high-grade tumors

Peripheral nerve sheath tumors (PNSTs) arising in neurofibromatosis type 1 range from benign to malignant, and the mechanisms of this heterogeneity remain unclear. This integrated germline and somatic analysis covered 208 samples (74 blood and 134 tumors) from 74 patients, using a custom NF-focused panel. It identified 55 pathogenic germline NF1 variants, eight of them unreported, with recurrent NF1 microdeletions involving SUZ12 in high-grade and premalignant tumors; biallelic NF1 inactivation occurred in 90 of 124 tumors (72.6%), most often through loss of heterozygosity. In 30 individuals, distinct tumors typically carried different NF1 second-hit events despite a shared germline background, whereas histologically distinct components within a tumor shared NF1 alterations and sequentially acquired CDKN2A and EED alterations.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

The useful message is lesion-to-lesion heterogeneity: the shared germline variant does not predict the second hit, which argues, according to the authors, for lesion-specific genomic evaluation. The series remains 74 patients analysed with a targeted panel, and the enrichment of NF1 domains by grade is partly presented as a trend. The abstract shows no direct consequence for surveillance or treatment: the contribution is mainly one of understanding, notably of stepwise progression to malignancy.

Analysis by Dr Thibaut Benquey