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Hereditary defects of the conotruncal septum in keeshond dogs: Pathologic and genetic studies

1974; Elsevier BV; Volume: 34; Issue: 2 Linguagem: Inglês

10.1016/0002-9149(74)90198-2

1879-1913

Donald F. Patterson, Robert L. Pyle, Lodewyk Van Mierop, Julius Melbin, Marcia Olson,

Congenital Heart Disease Studies

Pathologic studies of a hereditary cardiovascular defect in Keeshond dogs demonstrated a spectrum of malformations, primarily involving the ventricular outflow tracts. Lesions ranged from subclinicai defects of the crista supraventricularis to end-stage tetralogy of Fallot and included isolated ventricular septal defects and pulmonic stenosis. The spectrum can be explained by assuming that the anatomic variations represent different thresholds along a continuum of maldevelopment producing hypoplasia and malpositioning of the conotruncal septum. The results of breeding experiments conducted in a colony of Keeshond dogs with conotruncal septal defects confirmed the hereditary nature of the abnormality but were not consistent with any simple genetic hypothesis. Both the incidence and the severity of the conotruncal lesions increased with the severity of the parental defect. The results are shown to fit a polygenic model with three developmental thresholds, in which multiple genes act additively to produce a continuous distribution of maldevelopment involving the conotruncal septum. Lesions of increasing severity occur with an increasing "dose" of genes predisposing to conotruncal septal defects.