Effects of MTM1 mutation on respiration during direct stimulation. Dogs given intravenous doxapram to place the respiratory muscles at work. Representative flow volume loops captured after respiratory stimulation for individual (A) controls (N=2), dark blue loops and (B) XLMTM (N=4) dogs, red loops, at 17 weeks-of-age. (C) The flow-volume loop, with highlighted areas of measurement. XLMTM, X-linked myotubular myopathy.