Retrospective Clinical Analysis Of 6 Cases Of Andersen-Tawil Syndrome In China

Objective: To analyze the clinicalmanifestations,electrophysiological and genetic examination results of patients with Andersen-Tawil syndrome(ATS),in order to improve the understanding towards ATS.Materials and methods: 2 cases of patients diagnosed of ATS in the Neurology Department of Xi'an Hi Tech Hospital fromJanuary 1,2017 to January 1,2017 and 4 cases of patientswith ATS reported in literatures at home and abroad in recent 10 years were collected.A detailed analysis and summary ofclinical manifestations,ECG,EMG and genetics the 6 cases of Chinese ATS patients were performed.Results: 1.Clinical manifestations of ATS(1): periodic paralysis: 6 cases(100%)presented periodic paralysis,4 cases(66.67%)of whom demonstrated hypokalemic periodic paralysis and 2 cases(33.33%)normallyhypokalemic periodic paralysis,and no hyperkalemic periodic paralysis were detected;(2)Developmental deformity: 5 cases(83.33%)presented typical developmental deformity,among whom 3 cases(50%)demonstrated ocular hypertelorism,2 cases(33.33%)low auricle,1 case(16.67%)micrognathia,1 case(16.67%)growth retardation and microsomia,1 case(16.67%)camptodactyly,and 2(33.33%)presented one typical developmental deformity and 3 cases(50.00%)two typical developmental deformities.2.Electrocardiogram: 5 cases(83.33%)presented ventricular arrhythmia,including 3 cases(50.00%)with Q-T elongation,3 cases(50.00%)with widened U wave,4 cases(66.67%)with ventricular tachycardia and 3 cases(50.00%)with bidirectional ventricular tachycardia.3.EMG:(1)5 cases of patients underwent EMG,4 cases(80.00%)of whom showed decrease in the amplitude of CMAP;(2)2 cases participated in long range exercise evoked test,finding that CMAP amplitude decreasing by over 40% within 60 min.4.Genetics: 5 cases underwent genetic tests,and 5 cases(100%)were found to present heterozygous KCNJ2 mutations with the heterozygous mutation type of c.431G>C(p.G144A)?c.899 G>T(p.G300V)?c.11062C>T(p.P186L)?c.919A>G(p.M307V).Conclusions: the main clinical manifestations of ATS patients in our country are periodic paralysis,ventricular arrhythmia and developmental malformation.(1)Gene specific electrocardiographic changes: characterized by ventricular tachycardia,widened U wave,marked prolongation of Q-T interval and characteristic bidirectional ventricular tachycardia,which may cause cardiac syncope and cardiac arrest.(2)EMG changes: motor nerve conduction test showed reduced amplitude of CMAP,and long range exercise evoked testshowed CMAP amplitude decreasing by over 40%within 60 min,and the amplitude mainly decreasedwithin the first 20 minutes.(3)KCNJ2 gene test facilitates diagnosis,and the type of gene mutation is c.431G>C(p.G144A)?c.899 G>T(p.G300V)?c.11062C>T(p.P186L)?c.919A>G(p.M307V).