SEVERE RESISTANT HYPOMAGNESEMIA AS THE FIRST CLINICAL PRESENTATION OF 17Q12 MICRODELETION SYNDROME

Abstract

SESSION TITLE: Medical Student/Resident Critical Care Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Hypomagnesemia occurs with decreased gastrointestinal absorption, transcellular shifts, and increased renal excretion. It is often associated with other electrolyte abnormalities including hypokalemia, hypocalcemia, and alkalosis. Hypomagnesemia is seen in patients with certain genetic syndromes and antifungals, chemotherapeutics, and diuretics use. We describe a patient who presented with symptomatic, severe, resistant hypomagnesemia and was found to have 17q12 microdeletion syndrome. CASE PRESENTATION: The patient is a 43 year-old man with essential hypertension, ureteropelvic junction obstruction (repaired in childhood), and chronic hydronephrosis who was noted to have hypomagnesemia on routine blood work 3 years prior to presentation. He was admitted for fatigue, palpitations, and multiple presyncopal episodes. Vital signs showed blood pressure of 168/79mmHg and pulse of 69. The patient had a marfanoid habitus and mild cognitive impairment. Initial blood work showed a magnesium of 1.1 mg/dL, bicarbonate of 33 mmol/L, potassium of 3.3 mmol/L, creatinine of 1.3 mg/dL, AST 68 U/L, ALT 54 U/L, alkaline phosphatase of 122 U/L, and HbA1c of 5.4%. Renal ultrasound showed mild right hydronephrosis and severe left hydronephrosis with obstruction at the ureteropelvic junction. A 24-hour urine magnesium was elevated (211mg/24hrs), consistent with urinary magnesium wasting. The patient was started on magnesium chloride supplements and amiloride. He completed a 48 hour Holter monitor, exercise stress test, and echocardiogram for syncopal episodes. This showed frequent premature ventricular contractions. Hepatology evaluation for persistently elevated alkaline phosphatase and liver enzymes was negative for biliary pathology. Causes of his magnesium wasting were considered including Bartter’s syndrome, Gitelman’s syndrome or other calcium sensing receptor mutations. He had genetic testing and found to have 17q12 microdeletion syndrome. DISCUSSION: 17q12 deletion syndrome is associated with maturity onset diabetes of the young, urinary tract abnormalities, and cognitive impairment. Hepatocyte nuclear factor 1 B (HNF1B) is a transcription gene within the 17q12 deletion that has toxic effects on the distal convoluted tubule where magnesium transport is regulated. It is thought the HNF1B defect worsens with age which is why patients typically present with hypomagnesemia in the 5th decade of life. Severe coronary calcification and pancreatic atrophy have been reported with this syndrome as well. CONCLUSIONS: Hypomagnesemia can present as a wide spectrum of atypical symptoms. When resistant hypomagnesemia persists without obvious underlying etiology, genetic causes must be considered. Reference #1: Li, H. J., Groden, C., Hoenig, M. P., Ray, E. C., Ferreira, C. R., Gahl, W., & Novacic, D. (2019). Case report: extreme coronary calcifications and hypomagnesemia in a patient with a 17q12 deletion involving HNF1B. BMC nephrology, 20(1), 1-6. Reference #2: Agus, Z. S. (1999). Hypomagnesemia. Journal of the American Society of Nephrology, 10(7), 1616-1622. DISCLOSURES: No relevant relationships by Karthik Gonuguntla, source=Web Response No relevant relationships by Nikola Perosevic, source=Web Response No relevant relationships by Sruti Velamakanni, source=Web Response Subinvestigator relationship with Davita Clinical Research Please note: $1001 - $5000 Added 05/31/2020 by Christine Vigneault, source=Web Response, value=Grant/Research Support