Childhood hypophosphatasia with myopathy: clinical report with recent update

Hypophosphatasia is a rare genetic disease with low tissue nonspeficic alkaline phosphatase activity (TNSALP), due to ALPL gene mutation. There are 6 clinical forms. Childhood form is caractheri­zed by short stature, premature loss of decidous teeth and diffuse bone pain associated with a pathological bone fracture in the past. Laboratory findings present low serum le­vel of alkaline phosphatase and high levels of serum and urinary extracelular metabolytes. It is described a case report of a 34 years old woman with previous diag­nosis of childhood hypophosphatasia, caryotype 46,XX, and molecular screening for the gene ALPL with a c.1426>A p.E476K mutation, who complained of proximal muscular weakness intensified with the cold weather, exercise, and a waddling gait. The electromyography was compatible with myopathy but the muscle biopsy was normal. The serum crea­tine kinase levels were normal, as well as the others muscle enzymes. Clinical and laboratory/ /imaging dissociation is frequent in other metabo­lic bone diseases as osteomalacia. The rarity of this case of childhood hypophosphatasia with “de novo” non-progressive myopathy of the lower limbs, justified a case report with literature revision.