Few examples- Heritable connective-tissue disorders,Ehlers-Danlos syndrome type IV,Fibromuscular dysplasia,Cystic medial necrosis,Marfan syndrome
Spontaneous internal carotid artery dissection is a common cause of
ischemic stroke in patients younger than 50 years and accounts for up to 25% of
ischemic strokes in young and middle-aged patients.
Now you could understand why you were tested for various antibodies.