GNE myopathy is a distal myopathy that is thought to be caused by a mutation in the GNE gene that encodes an enzyme in the biosynthetic process of aceneuramic acid (typical sialic acid). It is an extremely rare progressive muscle disease, often occurring in the late teens to 30s, usually affecting the distal lower leg, especially the extensor muscles such as the tibialis anterior muscle, first, and weakness in both upper and lower limbs. However, the weakness of the quadriceps femoris is usually gradual. Although there are large individual differences, health management and deterioration of QOL will eventually become a problem, and in severe cases, constant assistance is required in daily life.~A double-blind comparative study conducted in Japan provided results suggesting efficacy, but the efficacy could not be confirmed in a large-scale international clinical trial, so this study is decided to be conducted. Oral administration of aceneuramic acid tablets 500 mg (SA-ER tablets) or placebo tablets of the same appearance, 4 tablets at a time, 3 times a day for 48 weeks will be examined for differences in efficacy. The target was a total of 10 cases, 7 cases in the active drug group, and 3 in the placebo group. The amount of change in upper extremity composite score (the sum of the average of the right and left HHD scores for grip, shoulder abductors, elbow flexors and elbow extensors) was used, and the secondary endpoints were the doctor's comprehensive evaluation and the GNE myopathy functional activity scale.
GNE myopathy is a distal myopathy that is thought to be caused by a mutation in the GNE gene that encodes an enzyme in the biosynthetic process of aceneuramic acid (typical sialic acid). The investigators will examine the efficacy and safety of aceneuramic acid (SA-ER tablets) 6g daily for 48 weeks in patients with GNE myopathy in a placebo-controlled, double-blind, controlled trial.