The onset and distribution of muscle weakness in our patient involving only distal lower limbs in the fourth decade of life is quite different from that observed in individual patients carrying the same RYR1 variant [32] or the adjacent p.(Phe4808Asn) mutation [33–35] in which muscle weakness was proximal starting during early childhood [32, 34, 35] or there was only a susceptibility to MH without clinical myopathy [33]. This evidence concerns the gene RYR1 and myopathy.