Marfan syndrome is a connective tissue disorder observed to some degree in one out of about every 10,000 persons. It is caused by a gene abnormality, and in 1991 researchers identified a gene linked to this disease. An affected person has about a 50% chance of passing it to offspring. Symptoms include abnormal tallness compared with unaffected family members, disproportionately long limbs, fingers, and head, an excessively curved spine and breastbone, loose joints, and small muscles. Affected persons are likely to have a weakened aorta and heart valves and are prone to cardiac infections. Hormones may aid in reducing growth if the symptoms appear before puberty. Drugs can help to relieve stress on the aorta, but surgery may be needed. No diagnostic test exists for the condition prior to the appearance of symptoms.