They found out that the pathogenic mutation was only present in vascular tissue, but not in blood cells.
DNA replication errors occur all the time, even in multi-cellular organisms. Some of them lead to cancer, but most of them are either lethal (for the cell), or, most of the time, innocuous.
The most likely scenario for the abdominal aortic aneurism is the following: A mutation can occur during organogenesis, in utero. The earlier it occurs, the more cells will be affected. Said mutation can be initially benign, but become problematic in the long run. If the mutation occurs after the differentiation between fibroblasts and blood progenitor cells, only affecting the former, you get the scenario described in the ScienceDaily article.
DNA replication errors occur all the time, even in multi-cellular organisms. Some of them lead to cancer, but most of them are either lethal (for the cell), or, most of the time, innocuous.
The most likely scenario for the abdominal aortic aneurism is the following: A mutation can occur during organogenesis, in utero. The earlier it occurs, the more cells will be affected. Said mutation can be initially benign, but become problematic in the long run. If the mutation occurs after the differentiation between fibroblasts and blood progenitor cells, only affecting the former, you get the scenario described in the ScienceDaily article.