Another possibility is that this association represents only an epiphenomenon since, in our study, a cause-effect relationship between polymorphism and mortality was not established.
However, headache has not been sufficiently studied as a cause of morbidity in the developing world.
Troubled sleep is a commonly cited consequence of adolescent drug use, but it has rarely been studied as a cause.
However, given the retrospective nature of these studies, a cause and effect relationship cannot be definitively determined.
Prof Jane Wardle, of CRUK's Health Behaviour Research Centre at University College London, who was one of the authors of the paper, said: "This study was a cause for celebration and concern.
GTPBP5 bears further study as a cause of TEF/EA accompanied by other malformations.
If so, the data from this study represent a cause for concern for the future.
Taken together, these observations show that the P-element insertion mutants we study cause a reduced expression of the Hsp83 gene in three different genetic backgrounds.
If you are studying a simple system, then cause and effect is relatively easy to establish.
Short staffing was reported by six studies as a cause of MAEs [ 42, 43, 45, 51, 64, 78, 82].
