Abstract
1. A child is described who presented with very severe rickets and gross myopathy. The clinical, biochemical and radiological signs were identical with those to be expected of a very chronic and severe vitamin D deficiency. The child's diet, however, had been normal.
2. All the pathological signs, except for residual dwarfism and leg bowing, disappeared on treatment with very large doses of vitamin D2. Ordinary anti-rachitic doses had no effect.
3. We suggest that this child demonstrates a true resistance to the action of vitamin D and that the defect is permanent. The findings in two similar patients that we have seen suggest that the condition is inherited as an autosomal recessive gene, and that it may be the same disease as that described in the continental literature as "hereditäre pseudo-mangelrachitis" and by other names.
4. The disease seems distinct clinically and biochemically from the disease originally described under the name "vitamin resistant rickets," which does not respond so well to massive vitamin D therapy and which is usually inherited as a sex-linked dominant gene.
