Molecular profiling of pediatric meningiomas shows tumor characteristics distinct from adult meningiomas.

In contrast to adults, meningiomas are uncommon tumors in childhood and adolescence. Whether adult and pediatric meningiomas differ on a molecular level is unclear. Here we report detailed genomic analyses of 37 pediatric meningiomas by sequencing and DNA methylation profiling. Histologically, the series was dominated by meningioma subtypes with aggressive behavior, with 70% of patients suffering from WHO grade II or III meningiomas. The most frequent cytogenetic aberrations were loss of chromosomes 22 (23/37 [62%]), 1 (9/37 [24%]), 18 (7/37 [19%]), and 14 (5/37 [14%]). Tumors with NF2 alterations exhibited overall increased chromosomal instability. Unsupervised clustering of DNA methylation profiles revealed separation into three groups: designated group 1 composed of clear cell and papillary meningiomas, whereas group 2A comprised predominantly atypical meningiomas and group 2B enriched for rare high-grade subtypes (rhabdoid, chordoid). Meningiomas from NF2 patients clustered exclusively within groups 1 and 2A. When compared with a dataset of 105 adult meningiomas, the pediatric meningiomas largely grouped separately. Targeted panel DNA sequencing of 34 tumors revealed frequent NF2 alterations, while other typical alterations found in adult non-NF2 tumors were absent. These data demonstrate that pediatric meningiomas are characterized by molecular features distinct from adult tumors.

Genetic Regulation of PCSK9 (Proprotein Convertase Subtilisin/Kexin Type 9) Plasma Levels and Its Impact on Atherosclerotic Vascular Disease Phenotypes.

BACKGROUND: Inhibition of PCSK9 (proprotein convertase subtilisin/kexin type 9) is a novel strategy to treat hypercholesterolemia and reduce cardiovascular events. However, the potential role of circulating plasma PCSK9 concentrations as a diagnostic and predictive biomarker remains uncertain as of now. Here, we aimed to identify genetic variants associated with plasma PCSK9 and investigate possible causal effects on atherosclerotic vascular disease phenotypes. METHODS: We performed the first genome-wide association study of plasma PCSK9 levels in a cohort of suspected and confirmed coronary artery disease (LIFE-Heart; n=3290). RESULTS: Several independent variants at the PCSK9 gene locus were associated with circulating PCSK9 levels at genome-wide significance (lead SNP rs11591147, PCSK9-R46L; P=1.94×10-17). We discovered 4 independent PCSK9 SNPs explaining 4.4% of the variance of plasma PCSK9. In addition, we identified a genome-wide significant locus at chromosome 7p22.1 (rs6957201; P=7.01×10-9) and 7 suggestive hits (P<1×10-6). Using MR (Mendelian Randomization), we detected significant causal effects of circulating PCSK9 on coronary artery disease status and severity, carotid plaques, and intima-media thickness. CONCLUSIONS: Variants at the PCSK9 gene locus seem to be the major genetic determinants of plasma PCSK9 levels with 4 independent variants at the PCSK9 gene locus expressing allelic heterogeneity. The detected MR estimates support the hypothesis of a causal effect of PCSK9 on coronary artery disease and other vascular phenotypes. Other observed genetic associations for PCSK9 require validation in independent cohorts. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00497887.