Coding and non-coding variants in the SHOX2 gene in patients with early-onset atrial fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia with a strong genetic component. Molecular pathways involving the homeodomain transcription factor Shox2 control the development and function of the cardiac conduction system in mouse and zebrafish. Here we report the analysis of human SHOX2 as a potential susceptibility gene for early-onset AF. To identify causal variants and define the underlying mechanisms, results from 378 patients with early-onset AF before the age of 60 years were analyzed and compared to 1870 controls or reference datasets. We identified two missense mutations (p.G81E, p.H283Q), that were predicted as damaging. Transactivation studies using SHOX2 targets and phenotypic rescue experiments in zebrafish demonstrated that the p.H283Q mutation severely affects SHOX2 pacemaker function. We also demonstrate an association between a 3'UTR variant c.*28T>C of SHOX2 and AF (p = 0.00515). Patients carrying this variant present significantly longer PR intervals. Mechanistically, this variant creates a functional binding site for hsa-miR-92b-5p. Circulating hsa-miR-92b-5p plasma levels were significantly altered in AF patients carrying the 3'UTR variant (p = 0.0095). Finally, we demonstrate significantly reduced SHOX2 expression levels in right atrial appendages of AF patients compared to patients with sinus rhythm. Together, these results suggest a genetic contribution of SHOX2 in early-onset AF.

[Practical Year - Surgery in the Reformed Curriculum MaReCuM (Mannheim)]

Background: Since 2006 the practical year in the Mannheim Reformed Curriculum Medicine (MaReCuM) is divided into four quarters: the two required subjects (surgery and internal medicine), one elective and one of four offered fields in ambulatory medicine. Therefore students can more intensively focus on their preferences in the practical year. In the present article we describe the provided surgical training sites, the organisation of the practical year, the surgical training itself and the quality management. We provide answers to the following questions: does dividing the practical year into quarters have a (negative) influence on the grades of final exams; how interested, motivated and satisfied are students in the different (surgical) quarters of the practical year and in which quarter(s) can new generation staff be recruited? Methods: We used results of the final exams of three cohorts of the traditional Mannheim track and three cohorts of MaReCuM, as well as the results of the Mannheim Questionnaire of Satisfaction with Training Conditions in the Practical Year of Medical Education from the regular evaluation of three practical year cohorts within two years. Conclusions: Dividing the practical year into quarters is possible and can be organised together with the new "mandatory subject" ambulatory medicine. The introduction of quarters has no negative effects on the results of final exams. The assignment in the surgical field from students' perspectives with regard to motivation, interest, knowledge and satisfaction with training is comparable to surgical electives. Therefore recruitment of new staff is possible either in the surgical elective or in the surgical area of ambulatory medicine.