Collagen components in a case of Marfans syndrome

Collagen species of the aorta in a case of Marfans syndrome were studied to compare the constituents with normal controls. The collagenous components extracted from the ascending aorta with pepsin digestion were applied onto SDS-polyacrylamide gel electrophoresis to identify the collagen species. We examined a patient of 22 year-old man with a characteristic clinical manifestation of Marfans syndrome, 186 in height and 58 kg in weight, who has a giant aneurysm at a proximal region of ascending aorta. The patient was born by a normal delivery. He had abnormal chest deformity at his birth. His body length had started to grow much taller than the average at the age of 10 years. Severe diastolic murmur was listen at the maximum VI grade. On operation, the ascending part was found to be elastic soft and the diameter was directly measured as 13 cm. His mentality developed normally. Simply put, he suffered from the dilated ascending aorta with also the enlarged heart and showed long extremities. Elastic aortic tissues from his ascending aorta at operation were homogenized and suspended in a 0.5 M acetic acid solution. Collagen was extracted with repeated pepsin digestion and then fractionated with 0.7 M NaCl and 2.0 M 1). The collagen content was determined by the measurement of hydro-xyproline. Polyacrylamide gel electrophoresis was performed in the presence of SDS by a modification l) of the method originally described by Laemmli. Immunoblotting of the antigens was carried out after separation of the type VI collagen 2). It was found that a small amount of type VI collagen is present in the aorta of the Marfans syndrome. Type III collagen as well as type I consisted of large amounts of the total collagen. The pepsin-extractable type III collagen was predominantly found in the acidic 0.7 M NaCl precipitate in which it accounted 39-41 % of the total collagen. The proportion of type III to type I in the inner and outer layers were 39 : 60 and 35 : 65, respectively. Thus, the inner layer contained much more type III than the outer layer did (Fig. 1). The excess amount of type III collagen may relate a fragility of the medial layer in a case of Marfans syndrome. A possible lower synthesis of type I collagen in the disease may reduced the proportion of type I collagen as to type III collagen. Increased synthesis of type III collagen may be a possible cause of a fragility of the aortic tissue (Fig. 2). The filamentous fibrils are abundant in vascular tissue, which may