Cavernous malformations (CMs) affecting the central nervous system occur in approximately 0.16% to 0.4% of the general population. The majority (85%) of the CMs are in a sporadic form, but the genetic background of sporadic CMs remains enigmatic. Of the 81 patients, 73 (90.1%) patients were detected carrying somatic missense variants in 2 genes: MAP3K3 and PIK3CA by whole-exome sequencing (WES). The mutation spectrum correlated with lesion size (P = 0.001), anatomical distribution (P < 0.001), MRI appearance (P = 0.004) and haemorrhage events (P = 0.006). PIK3CA mutation was a significant predictor of overt haemorrhage events (P = 0.003, OR = 11.252, 95% CI = 2.275-55.648). Enrichment of endothelial cell (EC) population was associated with a higher fractional abundance of the somatic mutations. Overexpression of the MAP3K3 mutation perturbed angiogenesis of EC models in vitro and zebrafish embryos in vivo. Distinct transcriptional signatures between different genetic subgroups of sporadic CMs were identified by single-cell RNA-sequencing (scRNA-seq) and verified by pathological staining. Significant apoptosis in MAP3K3 mutation carriers and overexpression of GDF15 and SERPINA5 in PIK3CA mutation carriers contributed to their phenotype. We identified activating MAP3K3 and PIK3CA somatic mutations in the majority (90.1%) of sporadic CMs and PIK3CA mutations could confer a higher risk for overt haemorrhage. Our data provide insights into genomic landscapes, propose a mechanistic explanation and underscore the possibility of a molecular classification for sporadic CMs.
Abnormal thyroid hormone (TH) function has been observed in all components of metabolic syndrome (MetS), but the mechanisms remain unclear. Altered genomic methylation status is closely related to MetS. Our aim was to determine whether methylation regulation in TH function–related genes is involved in MetS. In a small strictly selected cohort, low TH function was observed in MetS group, as well as lower
THRB
promoter methylation levels in peripheral blood leukocytes in a genome-wide methylation screening by Illumina 450K beadchip. The results of beadchip assay were then confirmed by Sequenom MassARRAY. Low
THRB
promoter methylation levels and low TH function in MetS were confirmed in another big-size validation cohort. Lower methylation levels were associated with higher
THRB
expression in peripheral blood leukocytes, and altered
THRB
promoter methylation status influenced its promoter activity and expression. In the MetS rat models constructed by high fat and high fructose diet, lower TH function was also observed, as well as lower
Thrb
promoter methylation levels. Furthermore, systematic inflammation observed in MetS was found to induce decreased
THRB
promoter methylation levels as well as corresponding
THRB
expression. Additionally, oral treatment with a physiological T3 dose mitigated hypertension and insulin resistance and partially alleviated hepatic steatosis and adipocyte hypertrophy in MetS rats. Low methylation levels of
THRB
promoter in peripheral blood leukocytes induced by systematic inflammation were involved in low TH function in MetS, whereas low TH function deteriorates MetS. This might serve as a novel therapeutic target of MetS.
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