Liu CC, et al. - Researchers here sought to report an association of the genetic variants in the APBB2gene with use of amphetamine in opioid-dependent patients undergoing methadone maintenance treatment (MMT). In the urine morphine test, a significantly higher percentage of positive results were observed among MMT patients who used amphetamine. Findings suggested that APBB2gene was associated with use of amphetamine among opioid dependent patients under MMT. A positive correlation was revealed between Single nucleotide polymorphism (SNP) rs4861075 and the severity of amphetamine use. In the urine morphine test negative patients, SNP rs78704328 was associated with plasma level of Aβ42 and Aβ42/Aβ40 ratio.