Craniometaphyseal dysplasia (CMD) is an infrequently occurring skeletal dysplasia often caused by a mutation in ANKH. The most common features are early and progressive
hyperostosis of craniofacial bones, which may cause obstruction of cranial nerves, and metaphyseal flaring of long bones. Rarely,
rickets has been associated with CMD, occurring early in the course of the disease. We report an infant with CMD who presented with elevated serum
alkaline phosphatase activity and low serum
phosphorus at age 1 month and radiographic changes of
rickets at 3 months of age. Further biochemical investigations revealed a high tubular reabsorption of
phosphate and suppressed FGF23 level congruent with a deficit of
phosphorus availability.
Therapy with
phosphorus was started at 4 months of age;
calcitriol was subsequently added upon emergence of
secondary hyperparathyroidism. A heterozygous pathogenic variant in ANKH c.1124_1126del (p.Ser375del) was identified. At 19 months of age
therapy was discontinued in view of the corrected biochemical profile and radiographic improvement of
rickets. ©The Authors. All rights reserved.