Connective Tissue Quiz

See Elastic Fibres. Option C is correct because fibrillin is the protein that forms the microfibrils around the core of every elastic fibre, and in Marfan syndrome the fibrillin gene (FBN1) is abnormal. Elastic fibres let tissues stretch and then recoil, like a rubber band, and they are especially important in artery walls and the dermis. Elastin makes up the main core of the fibre and the fibrillin microfibrils surround it, acting as a scaffold, so a fault in fibrillin weakens the whole fibre. Marfan syndrome is inherited in an autosomal dominant way, meaning one faulty copy of the gene is enough to cause it. People are abnormally tall with long, slender fingers (arachnodactyly, meaning spider-like fingers), are prone to joint dislocation, and, most seriously, can develop dilatation of the aortic root, the part of the aorta nearest the heart, which can lead to aortic dissection or rupture. Many different mutations in the gene have been reported.

• Protein: fibrillin forms the microfibrils around the core of elastic fibres.
• Gene: FBN1 is abnormal in Marfan syndrome.
• Inheritance: autosomal dominant.