Genetic counseling in osteogenesis imperfecta.

Counseling of families with osteogenesis imperfecta was approached largely through the classification and data provided by Sillence and associates. Accurate pedigree data and a knowledgeable clinical team that can identify the affected family members as being one of the four major types can produce highly accurate risk figures in nearly all instances. Antenatal diagnosis, particularly an oblique radiographic view of the abdomen, is likely to detect at least a portion of the severely affected cases and should be offered in nearly all instances; it is particularly important in Types II and III where the manifestations are often severe. Improved biochemical diagnostic techniques will undoubtedly permit the categorizing of Type III cases into those that are truly recessively inherited and those that are new, dominant mutations, and thus lead to significantly improved counseling. On the other hand, counseling for the other types will not be greatly altered by better tests, except that the definition of further subtypes in I and IV might provide a more accurate estimate of the burden for a specific family. It may also become possible to use improved biochemical studies for antenatal diagnosis through a variety of approaches. Finally, sufficient benefit from genetic counseling is realized to warrant the referral of all patients to an appropriate medical genetics center for counseling.