Question: Among the genes with nucleic acid metabolism defects, how many of them can be found in the vacuole?
SQL: SELECT COUNT(T1.GeneID) FROM Genes AS T1 INNER JOIN Classification AS T2 ON T1.GeneID = T2.GeneID WHERE T2.Localization = 'vacuole' AND T1.Phenotype = 'Nucleic acid metabolism defects'