Identification of a Novel Non-V600E BRAF Mutation in Papillary Thyroid Cancer

Papillary thyroid cancer (PTC) is a common endocrine malignancy, and its incidence is reported to be constantly increasing. BRAF mutation is detected in approximately 44% of PTCs, and the most common BRAF mutation is thymine (T) to adenine (A) missense mutation in nucleotide 1796 (T1796A, V600E). Although BRAFV600E represents 95% of all BRAF mutations, uncommon BRAF mutations have been reported in thyroid carcinomas and represent an alternative mechanism of BRAF activation with unclear clinical significance. We report a novel non-V600E mutation (c.1799_1812delinsAT, p.V600_W604delinsD), identified preoperatively with next-generation sequencing (NGS) on the material obtained with fine-needle aspiration cytology (FNAC) performed on a thyroid nodule cytologically suspicious for malignancy in a 35-year-old male patient. The presence of this new variant of BRAF mutation was subsequently confirmed in the postoperative phase by direct Sanger sequencing. In conclusion, we report a new non-V600E variant previously undetected in papillary thyroid cancer. In addition, this case report shows that the NGS technique on cytological tissue allows to detect the presence of rare mutations, thus increasing the diagnostic specificity of molecular analysis.

BL-MOL-AR Project, Preliminary Results about Liquid Biopsy: Molecular Approach Experience and Research Activity in Oncological Settings

Background  Liquid biopsy is mainly used to identify tumor cells in pulmonary neoplasms. It is more often used in research than in clinical practice. The BL-MOL-AR study aims to investigate the efficacy of next-generation sequencing (NGS) and clinical interpretation of the circulating free DNA (cfDNA) levels. This study reports the preliminary results from the first samples analyzed from patients affected by various neoplasms: lung, intestinal, mammary, gastric, biliary, and cutaneous. Methods  The Biopsia Liquida-Molecolare-Arezzo study aims to enroll cancer patients affected by various malignancies, including pulmonary, intestinal, advanced urothelial, biliary, breast, cutaneous, and gastric malignancies. Thirty-nine patients were included in this preliminary report. At time zero, a liquid biopsy is executed, and two types of NGS panels are performed, comprising 17 genes in panel 1, which is already used in the routine tissue setting, and 52 genes in panel 2. From the 7th month after enrollment, 10 sequential liquid biopsies are performed up to the 17th month. The variant allele frequency (%) and cfDNA levels (ng/mL) are measured in every plasmatic sample. Results  The NGS results obtained by different panels are similar even though the number of mutations is more concordant for lung pathologies. There are no significant differences in the actionability levels of the identified variants. Most of the molecular profiles of liquid biopsies reflect tissue data. Conclusions  Preliminary data from this study confirm the need to clarify the limitations and potential of liquid biopsy beyond the lung setting. Overall, parameters related to cfDNA levels and variant allele frequency could provide important indications for prognosis and disease monitoring.

Clinical phenotype and outcome of hypertrophic cardiomyopathy associated with thin-filament gene mutations

Background

Mild hypertrophy but increased arrhythmic risk characterizes the stereotypic phenotype proposed for hypertrophic cardiomyopathy (HCM) caused by thin-filament mutations. However, whether such clinical profile is different from more prevalent thick-filament–associated disease is unresolved.

Objectives

This study aimed to assess clinical features and outcomes in a large cohort of patients with HCM associated with thin-filament mutations compared with thick-filament HCM.

Methods

Adult HCM patients (age >18 years), 80 with thin-filament and 150 with thick-filament mutations, were followed for an average of 4.5 years.

Results

Compared with thick-filament HCM, patients with thin-filament mutations showed: 1) milder and atypically distributed left ventricular (LV) hypertrophy (maximal wall thickness 18 ± 5 mm vs. 24 ± 6 mm; p < 0.001) and less prevalent outflow tract obstruction (19% vs. 34%; p = 0.015); 2) higher rate of progression to New York Heart Association functional class III or IV (15% vs. 5%; p = 0.013); 3) higher prevalence of systolic dysfunction or restrictive LV filling at last evaluation (20% vs. 9%; p = 0.038); 4) 2.4-fold increase in prevalence of triphasic LV filling pattern (26% vs. 11%; p = 0.002); and 5) similar rates of malignant ventricular arrhythmias and sudden cardiac death (p = 0.593).

Conclusions

In adult HCM patients, thin-filament mutations are associated with increased likelihood of advanced LV dysfunction and heart failure compared with thick-filament disease, whereas arrhythmic risk in both subsets is comparable. Triphasic LV filling is particularly common in thin-filament HCM, reflecting profound diastolic dysfunction.

Novel α-actinin 2 variant associated with familial hypertrophic cardiomyopathy and juvenile atrial arrhythmias: a massively parallel sequencing study

BACKGROUND

Next-generation sequencing might be particularly advantageous in genetically heterogeneous conditions, such as hypertrophic cardiomyopathy (HCM), in which a considerable proportion of patients remain undiagnosed after Sanger. In this study, we present an Italian family with atypical HCM in which a novel disease-causing variant in α-actinin 2 (ACTN2) was identified by next-generation sequencing.

METHODS AND RESULTS

A large family spanning 4 generations was examined, exhibiting an autosomal dominant cardiomyopathic trait comprising a variable spectrum of (1) midapical HCM with restrictive evolution with marked biatrial dilatation, (2) early-onset atrial fibrillation and atrioventricular block, and (3) left ventricular noncompaction. In the proband, 48 disease genes for HCM, selected on the basis of published reports, were analyzed by targeted resequencing with a customized enrichment system. After bioinformatics analysis, 4 likely pathogenic variants were identified: TTN c.21977G>A (p.Arg7326Gln); TTN c.8749A>C (p.Thr2917Pro); ACTN2 c.683T>C (p.Met228Thr); and OBSCN c.13475T>G (p.Leu4492Arg). The novel variant ACTN2 c.683T>C (p.Met228Thr), located in the actin-binding domain, proved to be the only mutation fully cosegregating with the cardiomyopathic trait in 18 additional family members (of whom 11 clinically affected). ACTN2 c.683T>C (p.Met228Thr) was absent in 570 alleles of healthy controls and in 1000 Genomes Project and was labeled as Damaging by in silico analysis using polymorphism phenotyping v2, as Deleterious by sorts intolerant from tolerant, and as Disease-Causing by Mutation Taster.

CONCLUSIONS

A targeted next-generation sequencing approach allowed the identification of a novel ACTN2 variant associated with midapical HCM and juvenile onset of atrial fibrillation, emphasizing the potential of such approach in HCM diagnostic screening.

[Clinical relevance of genetic testing in hypertrophic cardiomyopathy]

More than two decades have elapsed since the discovery that sarcomere gene defects cause familial hypertrophic cardiomyopathy (HCM). Since then, genetic testing in HCM has developed, and become an important tool in clinical practice for diagnosis and prognosis overall in the Western countries. However its practical benefits are still understimated and clinicians often question about cost-effectiveness of genic testing in HCM patients and their families. This resistance is in contrast with considerable evidence supporting the role of genetics in tailoring management for HCM patients. Several current clinical uses of genetic testing in HCM, ranging from diagnosis in ambiguous situations, identification of disease phenocopies and HCM complex genotypes and confirmation of inherited disease in family members are reviewed. In the near future it is hoped that next generation sequencing will provide further diffusion of genetic testing in HCM and improvement in care.