CACNA2D2 and maple syrup urine disease: Consistently, CACNA2D2 mRNA also had a significant negative correlation with taurine (ρ = −0.420; p = 0.006), isoleucine (ρ = −0.377; p = 0.015) and glutamate (ρ = −0.378; p = 0.015), three AAs that are significantly increased in MSUD patients.