Mitral valve prolapse in sickle cell disease: Manifestation of a generalized connective tissue disorder

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Abstract
Previous studies have shown an association of sickle cell disease with generalized connective tissue disorders such as pscudoxanthoma elasticum. We recently documented an unexpectedly high prevalence of mitral valve prolapse, a connective tissue disorder, in sickle cell discase. To investigate this association, skin biopsies were analyzed from 32 sickle cell disease patients, 11 of whom had mitral prolapse. Total and type III collagen, collagen solubility, and uronic acid were not different between the patients with or without mitral prolapse (p > 0.05). Computerized morphometric quantitation of the volume fraction of elastic fibers was greater in sickle cell disease patients than in 10 normals (3.1 ± 0.1 mean ± SEM vs 2.0 ± 0.3%; p < 0.01) but less than in three patients with pseudoxanthoma elasticum (9.7 0.6%; p < 0.001). Desmosine radioimmunoassay (an index of elastic fibers) was greater in sickle cell disease patients with mitral prolapse than those without (239.3 ± 9.3 vs 171.7 ± 25.4 ng/mg wet weight; p < 0.02). Histopathologic grading showed a similar trend (p = 0.07). The combined probabilities of these three independent tests of elastic fiber quantity showed an increased elastic fiber concentration in mitral prolapse patients compared to those without mitral prolapse (p < 0.02). Thus, there is no evidence for a specific collagen defect; rather, sickle cell disease appears to be associated with a spectrum of elastic tissue disorders, a feature that could predispose to mitral valve prolapse.