RESUMEN
<p><b>OBJECTIVE</b>To ascertain histology changes of hereditary gingival fibromatosis (HGF) and the location of HGF gene.</p><p><b>METHODS</b>A pedigree analyses of HGF; and the ultrastructure of gingival overgrowth tissue was observed with electron microscopy. The overgrowth of the HGF gene was defined with microsatellite markers.</p><p><b>RESULTS</b>The connective tissue of HGF consisted of coarse collagen bundles and several kinds of cells arranged abnormally, such as: epithelial cells, smooth muscle cells and so on; the HGF locus had been mapped to chromosome 5q13-q22.</p><p><b>CONCLUSIONS</b>The gingival pathologic changes resemble "hamartoma"; the findings has implications for identification of the underlying genetic basis of HGF.</p>