A family is reported in which 5 individuals out of 2 generations were found to suffer from dysostosis cleidocranialis. In that kindred twins occurred twice, one twin pair being DZ and suffering from the disease, the other pair MZ and healthy. The number of affected family members is in agreement with the autosomal dominance of the trait as indicated by numerous earlier observations. The characteristics found were: reduced growth, macrocephalus with late fontanel occlusion, protrusive frontal

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... e, hypertelorism, dysplasia of the clavicles and the pelvis, retarded development of hand skeleton. There was a certain variability in the expression of the traits in both DZ twin sisters, particularly concerning the malformation of clavicles and pelvis. Their children showed rather uniform alterations concerning head and hand skeleton, clavicles and pelvis. Blood group tests performed did not reveal linked inheritance of the pathological trait and any of the used serological markers.