Abstract 53: A novel SLC12A1 gene mutation associated with primary hyperparathyroidism: A case report

Introduction: Primary hyperparathyroidism (PHPT) is a rare disease in paediatric age group with an estimated incidence of 2–5 cases in 100,000 live births. PHPT is characterized by excessive secretion of parathyroid hormone (PTH), responsible for hypercalcemia and hypophosphatemia. Most cases of PHPT are not hereditary and the familial PHPT accounts for 10–20% of cases. Case Description: A 14 year old male child brought with complaints of pain abdomen in left loin radiating to left groin and was associated with nausea and vomiting. On evaluation there was hypercalcemia (13.48 mg/dl (normal range-8.8 - 10.6 mg/dl), hypophosphatemia (3.61 mg/dl) (normal range -4.0 - 7.0 mg/dl) and elevated intact PTH (231.5 pg/ml (18.4 - 80.1 pg/mL) suggestive of PTH dependent hypercalcemia. Further 4D computerised tomography neck and sestamibi scan localised to right superior parathyroid adenoma and ultrasound scan didn't show parathyroid lesion. Subsequently he underwent right superior parathyroid adenectomy and serum calcium levels normalized after surgery. Clinical exome sequencing revealed heterozygous mutation c.2594T>C,P.phe86ser in the SLC12A1gene. Follow up after 2months revealed normocalcemia (9.6 mg/dl) (8.8 - 10.6 mg/dl). Discussion: Solute Carrier Family 12-member 1 (SLC12A1) gene encodes the sodium-potassium-chloride co-transporter (NKCC2) at the apical membrane of the thick ascending loop of Henle (TAL). Bartter's syndrome (BS) type I is a rare, renal tubular disorder associated with mutation of the SLC12A1 gene. The many allelic variants reported present with a spectrum of phenotypes, biochemical abnormalities and clinical severities. The case described suggest an association between primary hyperparathyroidism and loss of function mutation of SLC12A1, which may result in an aberrant threshold of the calcium sensing receptor at the level of the kidney Conclusion: We hereby report a novel mutation (c.2594T>C,P.phe86ser) associated with primary hyperparathyroidism in SLC12A1 gene. This case report adds to the existing literature for emerging role of SLC12A1 gene in calcium homeostasis.