UTRN and Duchenne muscular dystrophy: Confocal microscopy Z-stack analysis of two DMD patients' biopsies (patient 1 – age 4; patient 2 – age 8) that extended 8 μm beneath the surface of the dystrophic muscles revealed an inverse correlation between collagen type I and utrophin levels as depth into the tissue increased the level of collagen type I decreased and that of utrophin increased (Figure 2).