Prenatal diagnosis of antenatal Bartter syndrome: Another four case reports

Objective Bartter syndrome (BS) is a general term for a group of rare genetic disorders in which the defective kidneys have impaired ability to reabsorb salt, resulting in salt wasting, hypokalemia, and metabolic alkalosis. Prenatal diagnosis of antenatal BS is challenging because of the absence of structural anomalies in the fetus. We here report four cases of antenatal BS identified in utero by fetal exome analysis. Case report A total of four cases of antenatal BS were detected. All cases presented with idiopathic polyhydramnios, with no evidence of anomalies in the fetuses and placentae on serial ultrasounds, and excluding maternal diabetes. Polyhydramnios occurred at 23–24 weeks gestation, and the amniotic fluid volume continued to increase through the gestation in all cases. Premature rupture of membranes occurred at 26 weeks after amniocentesis in the first case and the pregnancy was terminated. In the second case, the pregnancy continued to near term after five amnioreductions performed at 25, 27, 29, 31 and 34 weeks respectively. Preterm labor occurred at 27 weeks in the third case, and the infant died at life of day 2. In the fourth case, the pregnancy continued to 30 weeks despite two amnioreductions done at 27 and 29 weeks, and the infant survived. Variants were detected in three genes, including SLC12A1 , KCNJ1 and BSND , corresponding to type 1, type 2, and type 4A. Conclusion Early-onset polyhydramnios without evidence of congenital anomalies should raise the clinical suspicion of BS. Prenatal genetic testing should be the option to confirm the diagnosis. Serial amnioreduction is recommended for the management to prevent perinatal complications.