[Genetic identification of patients and families with a long-QT syndrome: large regional differences in the result of 10 years]. / Genetische identificatie van patiënten en families met lange-QT-syndroom: grote regionale verschillen in de resultaten van 10 jaar.

OBJECTIVE: To determine the pattern of referral of Dutch patients with a long-QT syndrome (LQTS) on the basis of the postal codes of the LQTS probands from whom blood samples were submitted for DNA diagnostics. DESIGN: . Retrospective cohort study. METHOD: From the databases that are coupled to DNA diagnostics, all index patients were included for whom LQTS diagnostics had been requested during the period 1996-2005 at two clinical genetics centres (the University Medical Centre in Amsterdam and Maastricht University Hospital). The results were related to the postal code of the referred patient and corrected for the number of inhabitants of the region concerned. RESULTS: A total of 421 potential LQTS probands were included. Corrected for the numbers of inhabitants in the various postal codes, the number of referrals varied from 3 per million to 110 per million inhabitants. In view of the most recent estimated prevalence of LQTS (1:2000), this means that only 15% ofthe carriers of the LQTS mutation have so far been detected. CONCLUSION: There were large regional differences in the Netherlands in the requests for DNA diagnostics in patients with clinical LQTS. The overwhelming majority of the LQTS patients in the Netherlands have not yet been referred or identified. Expanding the available courses for general practitioners and cardiologists that are given by the staff of the cardiogenetic centres would seem to be indicated.