LETTER TO THE EDITOR
Late-onset primary LVH HCM versus cardiac fabry variant
Andrea Frustaci, MD, FCCP*,
Maurizio Pieroni, MD* and
Cristina Chimenti, MD*
* Institute of Cardiology, Catholic University, Largo A. Gemelli 8, 00168, RomeItaly
biocard{at}rm.unicatt.it
In their article that appeared in the August 2001 issue of JACC, Maron et al. (1) suggest that left ventricular hypertrophy (LVH) can be a late manifestation of hypertrophic cardiomyopathy (HCM) due to cardiac myosin-binding protein C (MyBP-C) mutations. However, the echocardiographically documented LVH developing in their midlife in patients with MyBP-C mutations cannot be attributed for certain to that genetic abnormality unless a histologic demonstration of HCM can be provided by LV endomyocardial biopsy.
In fact, penetrance of MyBP-C mutations in large series ranges between 37% and 71% even in patients over 50 years of age (2–4), and other genetic disorders that give rise to LVH in middle-aged patients also exist, such as the cardiac variant of Fabry disease (5,6). This last entity, although X-linked, can occur in both male and female patients (7), can account for up to 9% of patients with nonobstructive HCM (8,9) and can be diagnosed simply by assessment of the alpha-galactosidase A enzymatic activity in the peripheral blood. If Fabry disease was present even in a proportion of patients with presumed HCM, those patients could now benefit from galactose infusion (10) and/or enzyme replacement therapy (11).
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References
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1. Maron BJ, Niimura H, Casey SA, et al. Development of left ventricular hypertrophy in adults in hypertrophic cardiomyopathy caused by cardiac myosin-binding protein C gene mutations. J Am Coll Cardiol. 2001;38:315–321[Abstract/Free Full Text]
2. Charron P, Dubourg O, Desnos M, et al. Clinical features and prognostic implications of familial hypertrophic cardiomyopathy related to the cardiac myosin-binding protein C gene. Circulation. 1998;97:2230–2236[Abstract/Free Full Text]
3. Moolman JA, Reith S, Uhl K, et al. A newly created splice donor site in exon 25 of the MyBP-C gene is responsible for inherited hypertrophic cardiomyopathy with incomplete disease penetrance. Circulation. 2000;101:1396–1402[Abstract/Free Full Text]
4. Niimura H, Bachinski LL, Sangwatanaroj S, et al. Mutations in the gene for cardiac myosin-binding protein C and late-onset familial hypertrophic cardiomyopathy. N Engl J Med. 1998;338:1248–1257[CrossRef][Medline]
5. von Scheidt W, Eng CM, Fitzmaurice TF, et al. An atypical variant of Fabry’s disease with manifestations confined to the myocardium. N Engl J Med. 1991;324:395–399[Medline]
6. Nagao Y, Nakashima H, Fukuhara Y, et al. Hypertrophic cardiomyopathy in late-onset variant of Fabry disease with high residual activity of alpha-galactosidase A. Clin Genet. 1991;39:233–237[Medline]
7. Linhart A, Palecek T, Bultas J, et al. New insights in cardiac structural changes in patients with Fabry’s disease. Am Heart J. 2000;139:1101–1108[CrossRef][Medline]
8. Kuhn H, Kohler E, Hort W, Frenzel H. Concealed myocardial storage disease (Fabry’s disease): pitfalls in the diagnosis of hypertrophic nonobstructive cardiomyopathy (abstr). Circulation. 1982;Suppl II:117
9. Nakao S, Takenaka T, Maeda M, et al. An atypical variant of Fabry’s disease in men with left ventricular hypertrophy. N Engl J Med. 1995;333:288–293[CrossRef][Medline]
10. Frustaci A, Chimenti C, Ricci R, et al. Improvement in cardiac function in the cardiac variant of Fabry’s disease with galactose-infusion therapy. N Engl J Med. 2001;345:25–32[CrossRef][Medline]
11. Eng CM, Guffon N, Wilcox WR, et al. Safety and efficacy of recombinant human alpha-galactosidase A replacement therapy in Fabry’s disease. N Engl J Med. 2001;345:9–16[CrossRef][Medline]
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