Evidence for a quantitative genetic influence on the formation of aortic valves with two leaflets in the Syrian hamster

Abstract

SummaryWe studied the morphology of the aortic valves of 1,036 Syrian hamsters belonging to two families subjected to high endogamous pressure. Most (n=955) specimens were examined using a corrosion-cast technique. In the remaining 81 specimens, valvar morphology was assessed by means of a stereomicroscope, and in 18 of these cases a histologic study was also performed. In one of the families, a high proportion (30.5%) of hamsters had aortic valves with two leaflets, the aortic sinuses being oriented ventrodorsally. The percentage of such anomalous valves was found to be positively correlated with the inbreeding coefficient of specimens. In the other family, the occurrence of an aortic valve with two leaflets was a sporadic event. Stereoscopic and histologic observations demonstrated that, in 52 of 63 aortic valves with three leaflets, the ventral commissure between the right and left leaflets was partially fused, while in 10 other cases this commissure was completely fused. In addition, in nine of 18 aortic valves with two leaflets, there was a more or less well-developed raphe located in the ventral aortic sinus, approximately where the true ventral commissure would have been. Our observations suggest the existence of a continuous spectrum of aortic valvar morphology, ranging from a valve with three leaflets and no fusion of the ventral commissure to an aortic valve with two leaflets devoid of any raphe. This spectrum seems to be the result of the interaction of genetic and intrauterine environmental factors. Results of crosses between both related and unrelated hamsters suggest that the observed morphology in individuals is the result of quantitative inheritance.

Genetically alike Syrian hamsters display both bifoliate and trifoliate aortic valves

“…2009). The characteristics of this unique inbred family have been reported previously (Sans‐Coma et al. 1993b, 1996; Fernández et al.…”

“…1996). We determined the morphology of the aortic valves in the remaining 129 hamsters by making serial histological sections, again as described previously (Sans‐Coma et al. 1993b, 1996).…”

“…The Syrian hamsters we used belonged to a single inbred family having a high incidence of BAVs characterized by fusion of the right and left coronary aortic leaflets. In preceding papers, we showed that such valves are expressions of a trait, the variation of which takes the form of a phenotypic continuum (Sans‐Coma et al. 1993b, 1996; Fernández et al.…”

Bicuspid Aortic Valves With Different Spatial Orientations of the Leaflets Are Distinct Etiological Entities

“…Syrian hamsters belonged to a family subjected to systematic inbreeding in our laboratory by mating siblings (7,10). The incidence of BAVs in the mutant mice and inbred hamsters amounts to 32% and 58%, respectively.…”

“…Transverse and sagittal sections, 5 or 10 m thick, were serially cut to alternate histochemical and immunoperoxidase stainings in consecutive sections. The staining methods were described elsewhere (9,10,12). The antibodies used were monoclonal anti-smooth muscle (SM) ␣-actin (SigmaAldrich, Madrid, Spain), polyclonal anti-tenascin (gift from Dr. M. Chiquet, Basel, Switzerland), and peroxidaseconjugated antimouse immunoglobulin G (Sigma-Aldrich).…”