Objective: To exclude known gene mutation, 21 exon of SOS1 which had been certified by foreign country form 2 families with hereditary gingival fibromatosis.

• 摘要目的：对我国现有的2例家族遗传性牙龈纤维瘤病进行国外已证实的已知基因突变位点-SOS1基因21号外显子的排除性定位。