Can you get a stroke early in age from familial hypercholesterolemia. i've had known untreated high cholesterol since age 19. history of brain lesions?

Yes: Unfortunately familial hypercholesterolemia does put you at an increased risk for stroke and heart attack, but these risks can be decreased with cholesterol-lowering drugs. I can't comment on the brain lesions without seeing them, but it's possible that they're strokes. I hope you're following with a doctor about your cholesterol and cholesterol lowering meds. Good luck!