“…Thus these patients differ from the cases in which serum lactic acid and pyruvate are not increased (Pearson et al, 1961 ;Schmid and Hammaker, 1961 ; di Sant'Agnese, Andersen, and Metcalf, 1962), although they more closely resemble other recorded cases showing a slight increase (Schmid and Mahler, 1959 ;Mellick, Mahler, and Hughes, 1962). Our own experience suggests that a slight rise in lactic acid in the serum indicates a glycogen myopathy.…”