[A possible same genetic defect in two Niemann-Pick disease model mice].

We found two Niemann-Pick disease model mouse species, NCTR-BALB/c mouse and SPM mouse. NCTR-BALB/c mouse is known as a model mouse of Niemann-Pick disease type C, because cholesterol esterification is deficient in fibroblasts. On the other hand, SPM mouse has been thought as a model of Niemann-Pick disease type A. However, we disclosed cholesterol esterification in fibroblasts from SPM mice is also deficient. It indicates that two model mice could be caused by a same genetic deficiency. To test if the genetic defect of those mice are located in the same gene, we made NCTR-BALB/c mouse heterozygotes mate with SPM mouse heterozygotes. The F1 mice are investigated by lipid analysis, lysosomal enzyme assay, cholesterol esterification ratio, and electron microscopic study. Eleven in 42 F1 mice (25%) got affected, and the clinically affected F1 mice had the biological and morphological abnormalities which are seen in SPM and NCTR-BALB/c mice. These data suggest that genetic defects in NCTR-BALB/c and SPM mice are located in the same gene.