ESPE Abstracts

Background: Neonatal severe primary hyperparathyroidism (NSHPT, MIM 23900) is a potentially lethal autosomal recessive disorder characterized by severe hypercalcemia, markedly elevated serum PTH levels and skeletal abnormalities that include multiple fractures, demineralization and erosions. It is secondary to biallelic loss of function mutation in the CASR gene that encodes the calcium sensing receptor.

Case presentation: We identified a 10-day old baby boy born to first degree consanguineous Saudi parents who was hospitalized for poor feeding, lethargy and moderate dehydration. Found to have an incidental severe hypercalcemia 5.4 mmol/l (N:2.1–2.7), hypophosphatemia 0.76 mmol/l (N: 1–1.95) and markedly elevated PTH level 55.7 pmol/l (N:1.6–6.9), So the diagnosis of NSHPT was established. Medical treatment failed to restore eucalcemia so total parathyroidectomy with autotransplantation in the sternocleiodomastoid muscle was undertaken which resulted in resolution of clinical and biochemical picture. Molecular analysis of the CASR gene revealed a novel homozygous mutation ‘Gly695Val’. Unaffected parents were heterozygous carriers.

Conclusion: We, hereby, report the identification of a novel pathogenic homozygous loss of function mutation in the CASR gene in this saudi neonate with severe hypercalcemia which has never been described before. functional studies are needed to examine the role of this mutation in CASR acitivity.

Keywords: neonatal severe hyperparathyroidism, calcium sensing receptor, parathyroidectomy, autotransplantaion, parathyroid hormone.