FAMILIAL OCCURRENCE OF HYPERPLASTIC CALLUS IN OSTEOGENESIS IMPERFECTA

There is a hypothesis that hyperplastic callus (HC) in osteogenesis im perfecta (OI) is not merely a rare complication but could actually be inherited, although this idea has not yet been investigated. We descri bed two cases, a mother and son, with mild OI, normal scleral colour a nd no dentinogenesis imperfecta, who repeatedly had HC in their femur. Familial occurrence of HC was found in 13 cases in 5 families among 2 1 cases in 7 families with a familial background of OI in the literatu re (including this report). This is higher than the reported incidence of HC, 1.5% (5 cases of 333), and the mode of transmission is concomi tant with autosomal dominant inheritance in all these families, Since a review of 47 cases in the literature shows that HC occurs independen tly of scleral colour and the degree of bone fragility, it may be an a dditional criterion for subdivision within each type of the Sillence c lassification.