BMAL1 and Arrhythmia: Bmal1 expression was reduced by 65% in heterozygous Syt10-Cre mice (Syt10-Cre+/−; Bmal1loxp/loxp), which did not result in circadian arrhythmia, whereas Bmal1 transcript levels decreased by 83% in homozygous Syt10-Cre mice (Syt10-Cre+/+; Bmal1loxp/loxp) that was accompanied by arrhythmia [128].