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This study shows important data on the probability of diagnosing LQTS as ∼1:3300 in subjects aged 6 years and 1:1000 in those aged 12 years based on the HRS/EHRA/APHRS criteria.

Original ArticleBackground-A school-based electrocardiographic screening program has been developed in Japan. However, few data are available on the genetic characteristics of pediatric patients with long-QT syndrome who were diagnosed by this program. Methods and Results-A total of 117 unrelated probands aged ≤18 years were the subjects who were referred to our centers for genetic testing. Of these, 69 subjects diagnosed by the program formed the screened group. A total of 48 subjects were included in the clinical group and were diagnosed with long-QT syndrome-related symptoms, familial study, or by chance. Mutations were classified as radical, of high probability of pathogenicity, or of uncertain significance. Two subjects in the clinical group died. Genotypes were identified in 50 (72%) and 23 (48%) of subjects in the screened and clinical groups, respectively. Of the KCNQ1 or KCNH2 mutations, 31 of 33 (94%) in the screened group and 14 of 15 (93%) in the clinical group were radical and of high probability of pathogenicity. Prevalence of symptoms before (9/69 versus 31/48; P<0.0001) and after (12/69 versus 17/48; P=0.03) diagnosis was significantly lower in the screened group when compared with that in the clinical group although the QTc values, family history of long-QT syndrome, sudden death, and follow-up periods were not different between the groups. Conclusions-These data suggest that the screening program may be effective for early diagnosis of long-QT syndrome that may allow intervention before symptoms. In addition, screened patients should have follow-up equivalent to clinically identified patients. Thus, the aim of the present study was to determine the genetic characteristics of pediatric patients with LQTS who were diagnosed by a school-based screening program and whose genetic testing was performed and to compare results with subjects who visited hospitals because of the presence of LQTS-related symptoms, familial history, or who were diagnosed by chance. Methods Study PopulationThe study population included 117 unrelated probands ≤18 years of age who were referred to the Department of Pediatrics, Kagoshima University Hospital, Japan, between November 1993 and March 2005 or to the National Hospital Organization Kagoshima Medical Center from April 2005 to December 2012 for genetic evaluation. The population included 69 subjects who were screened by a school-based ECG screening program (Table 1). In the present study, LQTS-related symptoms were defined as syncope, aborted cardiac arrest, or sudden cardiac death at <30 years old. Subjects were divided into 2 groups on the basis of index events: subjects who were diagnosed by the schoolbased ECG screening program (screened group) and those who visited hospitals because of the presence of symptoms and family history or who were diagnosed by chance (clinical group; Table 1). Diagnosis of LQTS and Screening of QT Intervals in the School-based ECG Screening ProgramThe present study was a retrospective study, and diagnosis of LQTS and screening for prolo...