What is the most common condition among the female Americans?
the most common condition refers to MAX(COUNT(DESCRIPTION)); among the female Americans refer to PATIENT where gender = 'F' and ethnicity = 'american';
SELECT T2.DESCRIPTION FROM patients AS T1 INNER JOIN conditions AS T2 ON T1.patient = T2.PATIENT WHERE T1.gender = 'F' AND T1.ethnicity = 'american' GROUP BY T2.DESCRIPTION ORDER BY COUNT(T2.DESCRIPTION) DESC LIMIT 1