ABCB1 and hydronephrosis: Moreover, a single case study documented a temporary occurrence of bilateral hydronephrosis and acute kidney injury caused by a bladder sphincter spasm in a preterm newborn (GA 34 weeks); the pharmacogenomic screening revealed that the patient was homozygous for the C3435T polymorphism in the ABCB1 gene, linked to diminished P-glycoprotein activity.