title: Increased cardiac muscle fiber size and reduced cell number in Down syndrome: heart muscle cell number in Down syndrome.
abstract: The size of cardiac muscle fibers was determined for 15 patients with Down syndrome who did not have congenital heart disease and for 15 age- and sex-matched control patients by counting the number of cardiac muscle cells in specified areas of microscopic sections (method of Black-Schaffer and Turner). Mean ratio of muscle cells per unit area for the Down patients versus controls was 84.9%, with mean cross-sectional area of Down fibers 117.8% of control value and calculated mean volume of Down cells 127.7% of control value. Mean weights of Down hearts related to normal for age, versus control hearts, was 79.8% of control values. Calculated ratio of total cardiac muscle cell number in Down hearts was 62.5% of the value for controls. This value corresponds closely to the 62.4%, which can be calculated from Naeye's data on cardiac muscle fiber size in Down syndrome based on a point-count method, and is also close to published values for liver cell size and number and skeletal muscle nuclear number in Down syndrome. This study demonstrates that the Black-Schaffer and Turner method gives results equivalent to those of the point-count method for studies of cardiac muscle fiber size, and further supports the suggestion that chromosome 21 controls the size and number of at least certain cell types.
mesh_terms: D006332:Cardiomegaly / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009206:Myocardium / Q000473:pathology*; D009929:Organ Size