A significant increase in the activity of serum alkaline phosphatase is commonly reported in patients on long-term antiepileptic treatment or after any uncomplicated fracture. We report a case of a 35-year old male patient on five different anticonvulsant medications for treatment of the rare autosomal recessive neurodegenerative disorder, Unverricht-Lundborg disease. He presented with bilateral metatarsal fractures: however, his serum alkaline phosphatase activity remained below the lower limit of reference interval. Biochemical laboratory investigations revealed a long standing low serum alkaline phosphatase and raised plasma pyridoxal-5'-phosphate level. Sequencing of genomic DNA revealed that he is heterozygous for a mutation in the ALPL gene which is consistent with the diagnosis of hypophosphatasia. Keywords: Hypophosphatasia, Unverricht-Lundborg disease, Alkaline phosphatase enzyme
