Cushing's disease, also known as adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (PAs) that cause excess cortisol production, accounts for up to 85% of corticotrophin-dependent Cushing's syndrome cases. However, the genetic alterations in this disease are unclear. Here, we performed whole-exome sequencing of DNA derived from 12 ACTH-secreting PAs and matched blood samples, which revealed three types of somatic mutations in a candidate gene, USP8 (encoding ubiquitin-specific protease 8), exclusively in exon 14 in 8 of 12 ACTH-secreting PAs. We further evaluated somatic USP8 mutations in additional 258 PAs by Sanger sequencing. Targeted sequencing further identified a total of 17 types of USP8 variants in 67 of 108 ACTH-secreting PAs (62.04%). However, none of these mutations was detected in other types of PAs (n = 150). These mutations aggregate within the 14-3-3 binding motif of USP8 and disrupt the interaction between USP8 and 14-3-3 protein, resulting in an elevated capacity to protect EGFR from lysosomal degradation. Accordingly, PAs with mutated USP8 display a higher incidence of EGFR expression, elevated EGFR protein abundance and mRNA expression levels of POMC, which encodes the precursor of ACTH. PAs with mutated USP8 are significantly smaller in size and have higher ACTH production than wild-type PAs. In surgically resected primary USP8-mutated tumor cells, USP8 knockdown or blocking EGFR effectively attenuates ACTH secretion. Taken together, somatic gain-of-function USP8 mutations are common and contribute to ACTH overproduction in Cushing's disease. Inhibition of USP8 or EGFR is promising for treating USP8-mutated corticotrophin adenoma. Our study highlights the potentially functional mutated gene in Cushing's disease and provides insights into the therapeutics of this disease.

Esophageal squamous cell carcinoma is a major histological type of esophageal cancer, with distinct incidence and survival patterns among races. Although previous studies have characterized somatic mutations in this disease, a rigorous comparison between different patient populations has not been conducted. Here we sequence the samples of 316 Chinese patients, combine them with those from The Cancer Genome Atlas, and perform a comparative analysis between Asian and Caucasian patients. We find that mutated CSMD3 is associated with better prognosis in Asian patients. Applying a robust computational strategy that adjusts for both technical and biological confounding factors, we find that TP53, EP300, and NFE2L2 show higher mutational frequencies in Asian patients. Moreover, NFE2L2 mutations correlate with the allele status of a nearby high-Fst SNP, suggesting their potential interaction. Our study provides insights into the molecular basis underlying the striking racial disparities of this disease, and represents a general computational framework for such a cross-population comparison.

A hybrid allele between the carboxyl ester lipase gene (CEL) and its pseudogene, CELP (called CEL–HYB), generated by nonallelic homologous recombination between CEL intron 10 and CELP intron 10′, was found to increase susceptibility to chronic pancreatitis in a case–control study of patients of European ancestry. We attempted to replicate this finding in 3 independent cohorts from China, Japan, and India, but failed to detect the CEL–HYB allele in any of these populations. The CEL–HYB allele might therefore be an ethnic-specific risk factor for chronic pancreatitis. An alternative hybrid allele (CEL–HYB2) was identified in all 3 Asian populations (1.7% combined carrier frequency), but was not associated with chronic pancreatitis.

Background and Purpose—: Ischemic stroke, a complex and heterogeneous disease, is the second leading cause of death worldwide. Genetic factors and epigenetic modification contribute to the pathogenesis of this disease. However, the effects of epigenetic factors on this disease have not been systematically investigated. Our study was designed to identify methylation alterations in large-artery atherosclerotic stroke. Methods—: We conducted an epigenome-wide association analysis of large-artery atherosclerotic stroke using an Infinium HumanMethylation450 array (cases:controls=12:12), and the differentially methylated loci were validated in 2 cohorts (cases:controls, 110:122 and 191:191, respectively) using a Sequenom EpiTYPER assay. Results—: In the screening stage, 1012 differentially methylated CpG sites annotated in 672 genes were found to be significantly associated with large-artery atherosclerotic stroke (mean methylation difference >5%, P <0.01). Disease, Gene Ontology, and pathway analysis highlighted the enrichment of these differentially methylated genes in cardiovascular, metabolic, neurological and immune-related functional gene clusters ( P <0.05). We identified a differentially methylated region in the promoter of a humanin gene ( MTRNR2L8 , mean methylation difference=−13.01%, P =8.86×10 ^–14 ). We constructed a diagnostic prediction model that was based on the mean number of significantly changed CpG loci in MTRNR2L8 and showed high diagnostic specificity and sensitivity ( P <0.0001, area under the curve=0.774). Conclusions—: Together, these findings demonstrate that DNA methylation plays an important role in large-artery atherosclerotic stroke and that methylation of MTRNR2L8 is a potential therapeutic target and diagnostic biomarker for stroke.