(S (S (PP (IN Before) (BASENP (DT this) (NN study))) (COMMA ,) (S (S (BASENP (DT no) (NNS genes)) (VP (VBD had) (VP (VBN been) (VP (ADVP (RB directly)) (VP (VBN linked) (PP (TO to) (BASENP (NNS migraines)))))))) (COMMA ,) (SBAR (IN although) (S (NP (BASENP (NNS parts)) (PP (IN of) (NP (BASENP (DT the) (NN DNA)) (SBAR (WHNP (WDT that)) (S (VP (VBD raised) (BASENP (DT the) (JJ general) (NN risk)))))))) (VP (VBD had) (VP (VBN been) (VP (VBN found)))))))) (PERIOD .))