Database: thrombosis_prediction
Question: For the patients with an abnormal Ig M level, what is the most common disease they are diagnosed with?
SQL: SELECT T1.Diagnosis FROM Patient AS T1 INNER JOIN Laboratory AS T2 ON T1.ID = T2.ID WHERE T2.IGM NOT BETWEEN 40 AND 400 GROUP BY T1.Diagnosis ORDER BY COUNT(T1.Diagnosis) DESC LIMIT 1