[Clinical characteristics and genetic analysis of two children with neonatal severe hyperparathyroidism]

To explore the clinical features and genetic variants in two children with neonatal severe hyperparathyroidism (NSHPT).

Two children who were diagnosed with NSHPT at the Children's Hospital Affiliated to Xi'an Jiaotong University respectively in August 2019 and April 2022 were selected as the study subjects. Clinical data were collected, and both children were subjected to whole exome sequencing (WES). Candidate variants were verified by Sanger sequencing.

The main clinical features of the two children have included growth delay, hypotonia, hypercalcemia, hypophosphatemia, hyperparathyroid hormonemia, and renal calcium deposition. WES results showed that child 1 has harbored a homozygous c.1378_1G>A splicing variant of the CASR gene, which was unreported previously, whilst child 2 has harbored a homozygous c.2038C>T missense variant of the CASR gene, which was known to be likely pathogenic. Sanger sequencing confirmed that the parents of both children were heterozygous carriers.

The homozygous c.1378_1G>A and c.2038C>T variants of the CASR gene probably underlay the NSHPT in the two children. Discovery of the c.1378_1G>A variant has enriched the mutational spectrum of the CASR gene.