Asfotase Alfa Treatment in a 2-year-old Girl with Childhood Hypophosphatasia

Childhood hypophosphatasia (HPP) presents with bowing of the limbs, poor mobility, chronic pain, short stature, fractures, and motor impairment. Enzyme replacement therapy (ERT) provides improved pulmonary and physical function in life-threatening perinatal and infantile forms of HPP. However, treatment of those patients without life-threatening HPP is limited. This report describes the results of asfotase alfa (Strensiq (R), Alexion Pharmaceuticals, Inc.) treatment in a 6-year-old girl with childhood HPP, who presented with premature loss of primary teeth, low mobility, and chronic pain in the legs. Sequence analysis of the TNSALP gene revealed three heterozygous variants; c.526G>A (reported previously), c.1051G>C (novel), c.787T>C (reported previously). After a four-year follow-up under ERT, a marked reduction in leg pain and restlessness was observed and physical therapy assessments showed remarkable improvements in motor function, pain score, and quality of life. The treatment decision in childhood HPP is not as clear as in infantile and perinatal forms and it is mostly based on the clinical and radiological condition of the patient. In patients with childhood HPP without severe skeletal involvement but accompanying motor retardation, ERT may improve quality of life, motor functions, and daily activities.