Genetic marker study of dentinogenesis imperfecta.

DGI-II has been linked to the group specific component (Gc) on 4q and to interferon induced protein 10 (INP10) on 4q. We studied a three generation family with DGI-II along with a four generation DGI-II family to more precisely place DGI-II in the existing genetic map of 4q and to determine if genetic heterogeneity existed between various DGI-II families. Affected family members had brownish discoloration of the teeth, enamel fracturing and radiographic evidence of coronal and radicular pulp chamber obliteration. Thirteen polymorphic markers on 4q were studied including D4S35, D4S1, ALB, Gc, MGSA, AR, INP10, ADH3, FGFB, EGF, IL2, IF, and MNS. Gc and MNS blood group antigen typing were done using commercial SERA. Restriction fragment length polymorphism analysis using Southern blotting was done on the remaining markers. Pairwise linkage analysis was performed using the procedures of Morton. Tight linkage between DGI-II and eleven genetic markers, including Gc and EGF, was excluded. The tightest linkage with DGI-II was identified with the probe INP10 at theta = 0.0 with lod = +3.91. However, INP10 RFLP differences were detected between the families, such that DGI-II correlated with different alleles in each family. Results from this study demonstrated that DGI-II may possibly arise from more than one genetic mutation.