Orbital Metastasis and Intraocular Invasion of Malignant Mixed Tumor(Carcinosarcoma) of the Parotid Gland in a Child

fibrillin-rich microfibrils are susceptible to degradation by serine proteases, and the amino acid substitutions found in Marfan syndrome change the fragmentation patterns. Fibrillin degradation products generated by MMP activity provide conclusive evidence that these enzymes cause specific changes to assembled microfibrils. In Marfan syndrome, most of the mutations in fibrillin-1 are found within epidermal growth factor–like motifs and are predicted to disrupt calcium binding. These mutations may render fibrillin-1 more susceptible to proteolytic cleavage. Patients with isolated ectopia lentis may also have an increased susceptibility to zonular degradation. Structural modifications in fibrillin-rich microfibrils occur during aging of the human ciliary zonule. These age-related changes may account for the increased incidence of ocular disease in older patients with ectopia lentis. The hypothesis regarding the role of MMPs in lens subluxation implies that an imbalance of lens proteases and their antagonists may be involved in the development of ectopia lentis.