Sclerosteosis (OMIM 269500) is a rare autosomal recessive condition characterized by increased bone density associated with syndactyly. It is linked to a genetic defect in the SOST gene coding for sclerostin. So far, seven different loss-of-function mutations in SOST have been reported in patients with sclerosteosis. Recently, two mutations in LRP4 gene underlying sclerosteosis were identified, reflecting the genetic heterogeneity of this disease. We report here a 30-years-old Moroccan man presented with typical clinical and radiological features of sclerosteosis who carries a novel homozygous mutation in the SOST gene, characterized as a nonsense mutation (c.79C > T; p.Gln27∗) in exon 1 of the SOST gene. This is to our knowledge the first case of sclerosteosis reported from Morocco and North Africa.

BACKGROUND: Sclerosteosis (OMIM 269500) is a progressive, autosomal recessive, sclerosing bone disorder with a well defined phenotype. This phenotype is correlated with a deficiency in the protein product sclerostin, leading to bony overgrowth from the loss of inhibition of osteocyte function. Calvarial overgrowth can lead to cranial nerve palsies, visual impairment, and compression of the medulla at the foramen magnum. There is a presumption that calvarial thickening may lead to elevated intracranial pressure in these patients, although pressure measurements have not been published.
METHODS: The authors report the case of a 28-year-old Saudi Arabian man with sclerostosis, progressive headaches, and a cervical spinal cord syrinx. A cranial reconstruction was performed by aggressively thinning the thickened cortical bone, thereby expanding the intracranial space. The measured intracranial pressure was 25-40 mm HG under anesthesia.
CONCLUSIONS: After surgery, the patient had resolution of the headaches and radiographic near-resolution of the syrinx. The authors review their experience and the relevant literature with this rare case.