Andersen-Tawil syndrome: multi-system deep phenotyping of a large UK cohort

• Published in: Journal of neurology, neurosurgery and psychiatry Vol. 93; no. 6; p. A95
• Main Authors: Vivekanandam, Vinojini, Mannikko, Roope, Fialho, Doreen, Merve, A, Pattni, J, Marini-Bettolo, C, Savvatis, K, Behr, ER, Hanna, Michael, Matthews, Emma
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.06.2022; BMJ Publishing Group LTD
• Subjects: ABN Abstracts 2021; United Kingdom > UK
• ISSN: 0022-3050; 1468-330X
• DOI: 10.1136/jnnp-2022-ABN.308

Andersen-Tawil Syndrome (ATS) is a rare channelopathy caused by mutations in the KCNJ2 gene that encodes the ubiquitously expressed Kir2.1 potassium channel. We describe key findings in a large UK cohort of 52 patients, pertinent to the diagnosis and management of ATS. We report a new point prevalence of0.105 per 100 000 (increased from 0.08 per 100 000).While ATS has historically been considered a triad of episodic weakness, cardiac arrhythmias and dys- morphic features, we show that there is considerable variability to this phenotype. Pure cardiac or muscle phenotypes may exist. The absence of dysmorphic features does not exclude the diagnosis. Similarly, a normal long exercise test was seen in five patients.Importantly, we identify that the phenotype includes a significant risk of cardiac morbidity and mortality with 13% of our cohort requiring cardiac defibrillator or pacemaker insertion and an additional 23% reporting syncope. Syncope has been recently associated with an increased risk of life threatening arhythmic events in this cohort. Severe fixed myopathy was seen in a quarter of our cohort with 14% requiring a wheelchair or gait aid.We additionally describe novel neurological features and report eight new KCNJ2 variants with in vitro functional data. We provide key clinical insights and management recommendations. We also identify new features which are interesting areas for future research and collaboration.v.vivekanandam@ucl.ac.uk