Mc Cance syndrome.

The case is that of a 17-year old Moroccan boy presenting a growing delay and a vitamin D-resistant ricket (VRR). Osseous plain radiographs show demineralization with metaphyseal enlargement, thorax, legs and wrists deformities. Biology data confirms phosphocalcic anomalies with deep hypophosphatemia, normal phosphaturia, low phosphate renal reabsorption rate, normal plasma hydroxyvitamin D in addition to low calciuria. Clinical and biological data evokes an X-linked hypophosphatemia with ricket. This phenomenon is due to Phosphate regulating gene with Homolgy to Endopeptidase on the X chromosome (PHEX) gene mutation. No similar case was reported previously within the family, however, it would have been desirable to complement existing data with parents and siblings genetic study results. Pseudo-deficiency vitamin D resistant ricket (VRR), also referred to as Mc Cance syndrome, has a belated onset within children, and can be linked to a phosphate reabsorption anomaly. The aim of the treatment is to normalize phosphatemia with calcic and vitamin D (vit D) supplementation, so as to make up for calcium lack and avoid hypophosphatemia osseous complications (plasma vitamin D rate reduction and secondary hyperparathyroidism).