Hypercalcemia and CYP24A1 Gene Mutation Diagnosed in the 2nd Trimester of a Twin Pregnancy: A Case Report

Andris Romašovs (Coresponding Author), Lauma Jaunozola, Egija Berga-Švītiņa, Zanda Daneberga, Edvīns Miklaševičs, Valdis Pīrāgs (Coresponding Author)

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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Objective: Rare disease Background: Loss-of-function mutations of the CYP24A1 gene cause a deficiency of the CYP24A1 enzyme, which is involved in the catabolism of 1,25-dihydroxyvitamin D3. Patients who are CYP24A1 enzyme deficient are at increased risk of developing hypercalcemia during pregnancy and should avoid additional vitamin D supplementation. This case report provides additional information for managing and diagnosing patients with a CYP24A1 gene mutation. Case Report: A primipara woman with a twin pregnancy was admitted to our hospital for frequent hypertensive crises. She had no history of hypercalcemia-associated signs and symptoms except nephrocalcinosis, and reported no oth-er abnormalities or discomfort at presentation. Laboratory tests revealed that the parathyroid hormone level was suppressed and the serum calcium level was markedly increased. The 25-hydroxyvitamin D level was at the upper limit of the reference range while the 1,25-dihydroxyvitamin D3 level was elevated, suggesting a vitamin D catabolism disorder. A genetic test was performed and a homozygous likely pathogenic variant (based on the American College of Medical Genetics and Genomics guidelines) c.964G>A (p.Glu322Lys) was detected in the CYP24A1 gene (NM_000782.5). A cesarean section delivery was performed due to a single intrauterine demise at 33 weeks of gestation. The preterm newborn was diagnosed with transitional hypercalcemia and hyperphosphatemia; however, he was not treated, as he was asymptomatic. Conclusions: Patients with a CYP24A1 gene mutation are at increased risk of hypercalcemia and fetal demise; therefore, 25-hy-droxyvitamin D and calcium levels should be monitored in routine blood tests during pregnancy. Hypercalcemia in a newborn should be carefully evaluated and treated, as hypercalciuria can lead to nephrocalcinosis.

Original languageEnglish
Article numbere931116
Number of pages6
JournalThe American journal of case reports
Issue number1
Publication statusPublished - 18 Oct 2021


  • Cesarean Section
  • Female
  • Humans
  • Hypercalcemia/diagnosis
  • Infant, Newborn
  • Male
  • Mutation
  • Pregnancy
  • Pregnancy, Twin
  • Vitamin D3 24-Hydroxylase/genetics

Field of Science*

  • 3.2 Clinical medicine
  • 3.1 Basic medicine

Publication Type*

  • 1.1. Scientific article indexed in Web of Science and/or Scopus database


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