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ANA can be positive in many diseases like sle , sjogren`s disease , scleroderma
.So just with a symptom of an itch and ANA positive , you cant be sure of Lupus
So i advise you to get evaluated and examined by your Physician to come to a conclusion.Because you have a family history and ANA positive ,you have a risk.But your symptoms dont suffice a diagnosis.
Good Luck and Take care.