Provide the ID, sex, birthday of all patients diagnosed with 'RA' that are within the UN normal index.
within the UN normal index refers to UN < 30; Diagnosis = 'RA'
SELECT DISTINCT T1.ID, T1.SEX, T1.Birthday FROM Patient AS T1 INNER JOIN Laboratory AS T2 ON T1.ID = T2.ID WHERE T2.UN < 30 AND T1.Diagnosis = 'RA'