Lack of association between genetic polymorphisms in enzymes associated with folate metabolism and unexplained reduced sperm counts. oleh Celia Ravel, Sandra Chantot-Bastaraud, Clementine Chalmey, Luis Barreiro, Isabelle Aknin-Seifer, Jerome Pfeffer, Isabelle Berthaut, E Emmanuelle Mathieu, Jacqueline Mandelbaum, Jean-Pierre Siffroi, Ken McElreavey, Anu Bashamboo