How do you diagnose Marfan's?

• A tall and thin body frame, long and slender fingers, and long arms and legs.
• A curved spine (called scoliosis).
• Chest-wall deformities, such as a breast bone (sternum) that is caved in (indented) or sticking out (protruding). If the breast bone is indented, it may also be very narrow.
• Eye or vision problems, such as nearsightedness (only being able to see objects close up) or a detached retina that can lead to sudden loss of eyesight. A detached retina can be repaired by an eye surgeon.
• Disproportionate growth, meaning people with Marfan syndrome are usually very tall. This may be especially noticeable in children, because they may be much taller than other children their own age.
• Flat feet.
• Loose joints (called joint laxity) or being double jointed.
• Shortened muscles, tendons, and ligaments

The diagnosis of Marfan's is mostly a clinical one. There is no specific laboratory test for it that are used. The doctor look for the things listed above and reviews the patient and family history.