Furthermore, in DMD patients carbonic anhydrase 3 (CAH3), microtubule-associated-protein-4 and collagen type I-alpha 1 chain concentrations decline constantly over time; of interest, myosin light chain 3 (MLC3), electron transfer flavoprotein A (ETFA), troponin T, malate dehydrogenase 2 (MDH2), lactate dehydrogenase B and nestin plateaus in early teens; ETFA correlates with the score of the 6-min-walking-test, whereas MDH2, MLC3, CAH3 and nestin correlate with respiratory capacity [25]. Here, ETFA is linked to Duchenne muscular dystrophy.