A case with prenatal molecular diagnosis of X-linked transient antenatal Bartter syndrome

Early-onset polyhydramnios during pregnancy can be caused by X-linked transient antenatal Bartter syndrome. Most of the reported cases were molecularly diagnosed after birth, whereas few cases were diagnosed in the fetus period. We received a pregnant woman who had polyhydramnios detected by ultrasound imaging at 25 weeks of gestation, and treated with magnesium sulfate, indomethacin and an amnioreduction at 30 weeks of gestation, whereas amniotic fluid decreased spontaneously since 32 weeks of gestation. Prenatal molecular testing showed the fetus carried MAGED2 hemizygous variant c.967C>T [p. (Asp323*)] inherited from the mother. The preterm boy did not present with polyuria and electrolytes and acid-base imbalance in the early neonatal period, and had good development without polyuria at the age of 20 months. We presented the phenotypes of a Chinese case with a prenatal diagnosis of X-linked transient antenatal Bartter syndrome and his response to prenatal indomethacin treatment. Early identification of the condition helps to provide appropriate prenatal genetic counseling and postnatal management.