Initial comparison of genomic and cDNA sequence suggested the existence of genetic polymorphisms in the SP-D coding sequence, including one in the N-terminal propeptide domain (Thr11 compared with Met11 in the mature protein) and three additional differences within the collagen domain at positions 102, 160, and 186 [108] . The latter substitutions are conservative to the extent that they are not expected to disrupt the collagen helix. Floros Table 5 Increased SP-D accumulation or expression in animal models