The return of first-degree relatives of hypertrophic cardiomyopathy patients for HCM-related follow-up
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Hypertrophic cardiomyopathy is an inherited heart disease characterized by unexplained thickening of the left ventricle. Given its autosomal dominant method of inheritance, all first-degree family members of an HCM patient have a 50% risk of inheriting the disease. Since family members are at high risk for disease, we consider HCM a disease of not just a single patient, but of a whole family. Medical guidelines propose that all first-degree family members seek HCM-related follow-up. In most cases the follow-up involves longitudinal clinical screening. In some cases genetic testing is also indicated for relatives. In an observational study of 361 HCM patients and family members, who were seen at a specialized HCM clinic in the Cardiovascular Genomics Center at Brigham and Women’s Hospital in Boston, MA, we show that only 39% of relatives pursued any HCM-related follow-up. In general, children of HCM patients were more likely to seek follow-up than siblings or parents of HCM patients. In cases where genetic testing was indicated for family members, relatives were more likely to seek clinical than genetic screening. Yet, a large proportion did seek both types of testing. Genetic testing results seemed to influence the return by relatives for clinical follow-up. When a disease-causing genetic variant was identified in one individual, family members were more likely to have HCM-related follow-up than when no genetic variant was identified or no genetic testing was performed. This study provides initial insights into the causes for the low overall rate of familial follow-up for an inherited disorder. We recognize that relatives are lost to follow-up at the stage when the initial patient must transmit information about follow-up to his relatives. Of greater concern, our data suggests that patients may be misinterpreting negative genetic test results, which may reflect a mutation in a gene that has yet to be discovered, despite appropriate genetic counseling. Determining what factors influence familial follow-up allows us to reassess current processes, so as to ensure that more at-risk family members receive evaluations. Providing clinical care to the entire HCM population is important for treatment of symptoms and prevention of sudden cardiac death, the most devastating outcome caused by HCM. With the use of genetic testing we are also able to identify HCM patients before any symptoms arise. Studying this asymptomatic population allows us to learn more about disease biology and progression with the end goal of finding a medical therapy to reverse or prevent HCM.
Thesis (M.A.)--Boston University