Homocystinuria causes an inability to process amino acids properly. This genetic disorder has several forms, with the most common form resulting from a lack of the enzyme cystathionine beta-synthase. This form of the condition causes dislocation of the lens of the eye, skeletal abnormalities and an increased risk of blood clots. In some cases, children with this form of the disorder have learning difficulties and developmental delays. Other forms of homocystinuria result from a lack of other enzymes needed to process amino acids. These forms of the disorder cause seizures, movement problems, megaloblastic anemia and learning disabilities.
Homocystinuria results from mutations in the MTHFR, CBS, MTRR, and MTR genes. The CBS gene mutation disrupts the function of cystathionine beta-synthase in the body. This causes homocysteine levels to increase. The body excretes the excess in the urine, leading to elevated urine levels of homocysteine. The MTHFR, MTRR, and MTR genes help the body convert homocysteine to methionine. When mutations occur in these genes, the enzymes do not function properly. This results in elevated homocysteine levels.
Marfan syndrome is a connective tissue disorder that affects many parts of the body. Since connective tissues support the cartilage, ligaments, tendons and walls of the blood vessels, this disorder causes several problems. This condition results in an abnormal makeup of connective tissue, which means many structures do not have the stiffness necessary for proper function. Two of the most serious problems associated with Marfan syndrome are cardiac valve and blood vessel problems.
When the connective tissues in the heart are not strong enough, blood can leak backward through the aortic and mitral valves. This makes the heart work harder and can lead to enlargement of the heart muscle. Marfan syndrome also causes the walls of the major arteries to weaken. When the aorta weakens, it dilates, weakening the inner wall of the aorta. This increases the risk of an aortic tear, which allows blood to leak through the tear and separate the walls of an aorta. Marfan syndrome also increases the risk for an aortic aneurysm.