A Novel HRAS Mutation Independently Contributes to Left Ventricular Hypertrophy in a Family with a Known MYH7 Mutation.

Several genetic conditions can lead to left ventricular hypertrophy (LVH). Among them, hypertrophic cardiomyopathy (HCM), caused by mutations in sarcomere genes, is the most common inherited cardiac disease. Instead, RASopathies, a rare class of disorders characterized by neuro-cardio-facial-cutaneous abnormalities and sometimes presenting with LVH, are caused by mutations in the RAS-MAPK pathway. We report on a 62-years-old male who presented isolated severe obstructive LVH but did not carry the sarcomere mutation previously identified in his affected relatives. By exome sequencing, we detected a novel mutation in HRAS gene (NM_005343.2:p.Arg68Trp), present also in the proband's daughter, who showed mild LVH and severe intellectual disability. The cardiac phenotype was indistinguishable between family members carrying either mutation. In silico studies suggested that the mutated HRAS protein is constitutionally activated. Consistently, functional characterization in vitro confirmed elevated HRAS-GTP accumulation and downstream RAS-MAPK pathway activation that are known to drive cell proliferation in LVH. Our study emphasizes the role of RAS signaling in cardiac hypertrophy and highlights the complexity in differential diagnosis of RASopathies. In fact, the mild features of RASopathy and the recurrence of sarcomeric HCM in this family delayed the correct diagnosis until comprehensive genetic testing was performed.

Reflex Testing Rules for Cell Count and Differentiation of Nucleated Elements in Pleural and Ascitic Fluids on Sysmex XE-5000.

Flow cytometry is widely used in many laboratories for automated nucleated cell counts and their differentiation in body fluids. The implementation of new reflex testing rules on these automated instruments could open new frontiers in laboratory workflow, improving characterization of body fluids and clinical diagnosis and decreasing costs. Ascitic (150) and pleural (33) fluids were collected and assessed by XE-5000 and optical microscopy. Cell counts performed with the methods showed a Pearson's correlation of 0.98 (p < 0.0001), Passing-Bablok regression y = 0.99x + 2.44, and bias of 32.3. In ascitic fluids, the best diagnostic performance was found for polymorphonuclear and neutrophil counts on XE-5000, which exhibited areas under the curve (AUCs) 0.98 (p < 0.0001) and 0.99 (p < 0.0001), respectively. In pleural fluids the best diagnostic performance was found for polymorphonuclear percent parameter, which displayed 0.97 (p < 0.0001). Specific reflex test rules based on these parameters were characterized by 92% diagnostic concordance, 1.00 sensitivity, and 0.84 specificity with optical microscopy. The application of a set of reflex testing rules may improve the diagnostic performance of XE-5000, increasing its reliability for routine automated cell count in body fluids. We acknowledge that further studies should be planned to validate our findings according to clinical data.

BDNF and its receptors in human myasthenic thymus: implications for cell fate in thymic pathology.

Here we show that in myasthenic thymus several cell types, including thymic epithelial cells (TEC) and immune cells, were the source and the target of the neurotrophic factor brain-derived growth factor (BDNF). Interestingly, many actively proliferating medullary thymocytes expressed the receptor TrkB in vivo in involuted thymus, while this population was lost in hyperplastic or neoplastic thymuses. Furthermore, in hyperplastic thymuses the robust coordinated expression of BDNF in the germinal centers together with the receptor p75NTR on all proliferating B cells strongly suggests that this factor regulates germinal center reaction. Finally, all TEC dying of apoptosis expressed BDNF receptors, indicating that this neurotrophin is involved in TEC turnover. In thymomas both BDNF production and receptor expression in TEC were strongly hindered. This may represent an attempt of tumour escape from cell death.