Clinical and Molecular Characteristics of PRKACA L206R Mutant Cortisol-Producing Adenomas in Korean Patients

Background@#An activating mutation (c.617A>C/p.Lys206Arg, L206R) in protein kinase cAMP-activated catalytic subunit alpha (PRKACA) has been reported in 35% to 65% of cases of cortisol-producing adenomas (CPAs). We aimed to compare the clinical characteristics and transcriptome analysis between PRKACA L206R mutants and wild-type CPAs in Korea. @*Methods@#We included 57 subjects with CPAs who underwent adrenalectomy at Seoul National University Hospital. Sanger sequencing for PRKACA was conducted in 57 CPA tumor tissues. RNA sequencing was performed in 13 fresh-frozen tumor tissues. @*Results@#The prevalence of the PRKACA L206R mutation was 51% (29/57). The mean age of the study subjects was 42±12 years, and 87.7% (50/57) of the patients were female. Subjects with PRKACA L206R mutant CPAs showed smaller adenoma size (3.3±0.7 cm vs. 3.8±1.2 cm, P=0.059) and lower dehydroepiandrosterone sulfate levels (218±180 ng/mL vs. 1,511±3,307 ng/mL, P=0.001) than those with PRKACA wild-type CPAs. Transcriptome profiling identified 244 differentially expressed genes (DEGs) between PRKACA L206R mutant (n=8) and wild-type CPAs (n=5), including five upregulated and 239 downregulated genes in PRKACA L206R mutant CPAs (|fold change| ≥2, P<0.05). Among the upstream regulators of DEGs, CTNNB1 was the most significant transcription regulator. In several pathway analyses, the Wnt signaling pathway was downregulated and the steroid biosynthesis pathway was upregulated in PRKACA mutants. Protein-protein interaction analysis also showed that PRKACA downregulates Wnt signaling and upregulates steroid biosynthesis. @*Conclusion@#The PRKACA L206R mutation in CPAs causes high hormonal activity with a limited proliferative capacity, as supported by transcriptome profiling.

Findings of a 1303 Korean whole-exome sequencing study

Ethnically specific data on genetic variation are crucial for understanding human biology and for clinical interpretation of variant pathogenicity. We analyzed data obtained by deep sequencing 1303 Korean whole exomes; the data were generated by three independent whole exome sequencing projects (named the KOEX study). The primary focus of this study was to comprehensively analyze the variant statistics, investigate secondary findings that may have clinical actionability, and identify loci that should be cautiously interpreted for pathogenicity. A total of 495 729 unique variants were identified at exonic regions, including 169 380 nonsynonymous variants and 4356 frameshift insertion/deletions. Among these, 76 607 were novel coding variants. On average, each individual had 7136 nonsynonymous single-nucleotide variants and 74 frameshift insertion/deletions. We classified 13 pathogenic and 13 likely pathogenic variants in 56 genes that may have clinical actionability according to the guidelines of the American College of Medical Genetics and Genomics, and the Association for Molecular Pathology. The carrier frequency of these 26 variants was 2.46% (95% confidence interval 1.73–3.46). To identify loci that require cautious interpretation in clinical sequencing, we identified 18 genes that are prone to sequencing errors, and 671 genes that are highly polymorphic and carry excess nonsynonymous variants. The catalog of identified variants, its annotation and frequency information are publicly available (https://koex.snu.ac.kr). These findings should be useful resources for investigating ethnically specific characteristics in human health and disease.

No correlation between COMT genotype and entacapone benefi ts in Parkinson’s disease

Catechol-O-methyltransferase (COMT) inhibitors are used to increase the bioavailability of therapeutic L-dopa. We examined the effi cacy of entacapone in Parkinson’s disease patients who had daily “off” duration of ≤2 hours, and carried different COMT polymorphisms. A total of 168 PD patients were recruited from 19 centers. Subjects were administered with 100–200 mg of entacapone in combination with each dose of L-dopa for 2 months. The clinical effi cacy was evaluated based on the activities of daily living (ADL), score on the Unifi ed Parkinson’s Disease Rating Scale (UPDRS), Hoehn and Yahr (H&Y) stage, and Clinical Global Impression (CGI). COMT polymorphisms were genotyped. 3-O-methyldopa (3-OMD) levels were measured before and after the administration of entacapone. Entacapone administration produced signifi cant improvements in the total daily “on” duration, ADL, UPDRS score, and H&Y stage. Nineteen patients (11.3%) had the low-activity COMT genotype, 68 patients (40.5%) had the intermediate-activity COMT genotype, and 81patients (48.2%) had the high-activity COMT genotype. The effi cacy, and adverse effects of entacapone therapy did not differ between the three groups. There was a signifi cant reduction in 3-OMD, but this did not differ among the three genotypes. Entacapone provided an increased “on” duration and improved motor function in all COMT genotypes.