When all three cardinal features are present, the diagnosis is relatively easy to make. A family history showing first or second degree relatives with features of this condition is also helpful in making the diagnosis in the proband. Problems in diagnosis arise in young children who do not have a family history of Marfan syndrome, as the syndrome is not yet fully developed or expressed. This points to the importance of follow-up. As more clinical features develop with age, the diagnosis becomes definitive over time.
Facial features provide important clues to diagnosis.
These measurements are then compared with established norms. The length of the palpebral fissure is usually equal to the distance between the inner corners of the eyes. Hypotelorism refers to eyes that are close together. Hypertelorism refers to eyes that are far apart. Epicanthic fold refers to a fold of skin that overlies the inner comer of the eye.