Metaphyseal chondrodysplasia.

Any review of the metaphyseal chondrodysplasias is complicated by their variety and mainly unknown pathogenesis. The more familiar types display considerable clinical and radiological diversity: even more so the rarer disorders which still require complete definition, but differences in their mode of inheritance make diagnostic precision mandatory. These dysplasias present in infancy or in childhood, when the patient, usually dwarfed, may be proportionate, so that some forms may be confused with rickets or other lesions. Mental retardation is unusual, but the skin, hair, nails and facies provide valuable diagnostic features. Radiological abnormalities mainly affect the metaphyses of the shortened limb bones, less often the skull, vertebrae, pelvis, ribs and extremities, and sometimes their distribution may indicate the specific type of dysplasia. In a further complex group multiple systems are involved, notably the pancreas, intestine and lympho-reticular, causing malabsorption and haematological or immunological disorders.