CHL1 and acute lymphoblastic leukemia: A few contradictory reports found no increased risk of ALL or cALL with (markers of) reduced or delayed infectious exposures, and some actually described higher risk with more infectious exposures (Chan et al. 2002; Dockerty et al. 1999; Guise et al. 2005; Infante-Rivard et al. 2000; Neglia et al. 2000; Rosenbaum et al. 2000; Schüz et al. 1999).