Israel Medical Association Journal

The European Union defines rare diseases (RDs) as life-threatening or chronically debilitating conditions whose prevalence is less than 5 per 10,000. Moreover, for many RDs, including those of genetic origin, combined efforts are required to reduce morbidity or perinatal or early mortality, and address the considerable decline in an individual's quality of life and socioeconomic potential. Their specificities, i.e., a limited number of patients and scarcity of relevant knowledge and expertise, make RDs a unique condition which requires wide cooperation at a supranational level. Many steps were therefore taken to develop a network of European Reference Centers and to improve RDs coding and classification. In Italy, the RDs issue was addressed in 2001 with the development of a national network and a national registry coordinated by the National Center for RDs of the Italian National Institute of Health. Registries are an important resource for the development of appropriate public health policies and research on specific RDs. Research on RDs is essential for the development of novel therapeutic approaches and requires the involvement of scientific societies and patient organizations. Nevertheless, the management of patients with chronic RDs requires a qualified care network. The network for RDs of Piedmont and Aosta Valley (North-West Italy) represents an example of health care organization based on the availability of advanced therapies close to the patient’s home.

Background: Hypertrophic cardiomyopathy (HCM) is a familial disease with autosomal dominant inheritance and age-dependent penetrance, caused primarily by mutations of sarcomere genes. Because the clinical variability of HCM is related to its genetic heterogeneity, genetic studies may improve the diagnosis and prognostic evaluation in HCM.

Objectives: To analyze the impact of genetic diagnosis on the clinical management of HCM.

Methods: Genetic studies were performed for either research or clinical reasons. Once the disease-causing mutation was identified, the management plan was reevaluated. Family members were invited to receive genetic counseling and encouraged to be tested for the mutation.

Results: Ten mutations in sarcomere protein genes were identified in 9 probands: 2 novel and 8 previously described. Advanced heart failure or sudden death in a young person prompted the genetic study in 8 of the 9 families. Of 98 relatives available for genotyping, only 53 (54%) agreed to be tested. The compliance was higher in families with sudden death and lower in what appeared to be sporadic HCM or elderly-onset disease. Among the healthy we identified 9 carriers and 19 non-carriers. In 6 individuals the test result resolved an uncertainty about "possible HCM." In several cases the genetic result was also used for family planning and played a role in decisions on cardioverter-defibrillator implantation.

Conclusions: Recurrence of a same mutation in different families created an opportunity to apply the information from the literature for risk stratification of individual patients. We suggest that the clinical context determine the indication for genetic testing and interpretation of the results.