Chromosome 17q12 deletion including HNF1B presenting with recurrent severe cholestasis and profound hypomagnesemia during pregnancy: a case report

17q12 deletion features kidney/genital abnormalities, maturity-onset diabetes of the young, and bile duct hypoplasia. The condition may first present with severe cholestasis during pregnancy and is important to differentiate from classic intrahepatic cholestasis of pregnancy. A 30-year-old G3P0202 was referred at 27 weeks’ gestation with generalized weakness exacerbated in pregnancy. Obstetric history was significant for two prior spontaneous preterm births in the setting of a bicornuate uterus. The patient had severe cholestasis during both prior pregnancies. Family history is significant for a son with severe hydronephrosis and autism. The patient’s laboratories revealed critically low serum magnesium with severely elevated 24-hour-urine magnesium, suggesting renal magnesium wasting. She was treated with ongoing magnesium infusions. She was also diagnosed with severe cholestasis and gestational diabetes, and ultimately induced at 33 weeks due to intractable pruritis. The infant had a 35-day stay in the neonatal intensive care unit. Maternal chromosomal microarray returned with a pathogenic deletion of 17q12. The patient was advised to have her children evaluated with a geneticist. 17q12 deletion was the likely etiology of recurrent severe cholestasis complicating our patient’s prior pregnancies, and in the current pregnancy, along with renal dysfunction. Knowledge of 17q12 deletion is important for counseling of affected reproductive-aged women at risk of stillbirth associated with severe cholestasis and renal dysfunction during pregnancy. 17q12 deletion should be considered in the differential diagnosis when severely elevated bile acids are encountered during pregnancy, particularly in combination with maternal Mullerian anomaly or renal dysfunction, or fetal renal anomaly.