Background: Isolated hypoparathyroidism comprises a set of heterogeneous inherited diseases associated with abnormal calcium metabolism exclusively due to parathyroid hormone (PTH) deficiency. Isolated hypoparathyroidism can be either sporadic or inherited. Genetic causes that impair the synthesis or secretion of PTH, such as calcium-sensing receptor and PTH defects, or defects in the development of the parathyroid gland [glial cell missing 2, (GCM2)], have been established as causes of familial isolated hypoparathyroidism. Transcription factor GCM2 is a crucial regulator of parathyroid gland homeostasis. Transmission of pathogenic variants encoding GCM2 occurs in an autosomal recessive or dominant manner.
Case Presentation: Herein, we describe the case of a 12-year-old boy, born to consanguineous parents, who presented with abnormal movement during the first week of birth. Laboratory results revealed hypocalcemia, hyperphosphatemia, and low PTH levels. Genetic testing detected a novel homozygous variant in the GCM2 gene, c.391C>T (p.Arg131*). Although this variant has not been previously described, it is likely the pathogenic cause of this condition.
Conclusion: To the best of authors’ knowledge, this variant has not been listed in any database. Proper replacement therapy is likely to have good long-term outcomes for our patient.
Key words: GCM2, GCMB, hypoparathyroidism, c.391C>T, CASR, case report.
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