P. BETGHTON, H. HAMERSMA, B. J. CREMIN

SUMMARY Osteopetrosis is an unusual bone disorder in which the skeleton is radiographically dense. The condition is con­ ventionally subclassified into a benign autosomal dominant adult form and a malignant autosomal recessive variety. Among 14 affected individuals whom we have studied, 4 adults had an intermediate type of osteopetrosis in which serious complications included osteomyelitis, pathological fractures and dyshaemopoiesis. The funda­ mental biochemical relationship of this disorder with the classic forms of osteopetrosis is uncertain. The osteopetroses must be distinguished from other sclerosing bone conditions which have a different course and prognosis. Sclerosteosis and craniometaphyseal dysplasia, both of which occur in South Africa, are of practical importance in this context. S. Atr. med. l., 55, 659 (1979). The osteopetroses are a group of disorders in which skeletal sclerosis is the predominant radiological mani­ festation. The designation 'osteopetrosis' is sometimes applied loosely to a number of craniotubular dysplasias and hyperostoses. However, in the strict sense the term pertains to the infantile and adult forms of osteopetrosis, which are also sometimes known as Albers-Schonberg disease and 'marble bones'. The differentiation of osteopetrosis from other related disorders is largely dependent upon recognition of characteristic radiographic manifestations." ~ Diagnostic accuracy is important, as these conditions vary in their Genetic backeround, course and prognosis. The process of sclerosis may lead to bone marrow en­ croachment and dyshaemopoiesis, cranial nerve compres­ sion, pathological fractures and a propensity to osteomyeli­ tis. The infantile form of osteopetrosis, which is inherited as an autosomal recessive, is potentially lethal, while the adult autosomal dominant type is comparatively benign. lntermediate forms in which affected adults experience seriolls complications may be encountered. In spite of the clinical importance, this latter category has attracted