Infantile hypercalcemia with novel compound heterozygous mutation in SLC34A1 encoding renal sodium-phosphate cotransporter 2a: a case report

Idiopathic infantile hypercalcemia is characterized by hypercalcemia, dehydration, vomiting, and failure to thrive, and it is due to mutations in 24-hydroxylase (CYP24A1). Recently, mutations in sodium-phosphate cotransporter (SLC34A1) expressed in the kidney were discovered as an additional cause of idiopathic infantile hypercalcemia. This report describes a female infant admitted for evaluation of nephrocalcinosis. She presented with hypercalcemia, hypercalciuria, low intact parathyroid hormone level, and high 1,25-dihydroxyvitamin D3 level. Exome sequencing identified novel compound heterozygous mutations in SLC34A1 (c.1337G>A, c.1483C>T). The patient was treated with fluids for hydration, furosemide, a corticosteroid, and restriction of calcium/vitamin D intake. At the age of 7 months, the patient's calcium level was within the normal range, and hypercalciuria waxed and waned. Renal echogenicity improved on the follow-up ultrasonogram, and developmental delay was not noted. In cases of hypercalcemia with subsequent hypercalciuria, DNA analysis for SLC34A1 gene mutations and CYP24A1 gene mutations should be performed. Further studies are required to obtain long-term data on hypercalciuria and nephrocalcinosis.

A Case of Jacobsen Syndrome Presenting with a Huge Cephalhematoma and Thrombocytopenia after Birth / 임상소아혈액종양

Jacobsen syndrome (JS) is a contiguous gene syndrome resulting from a deletion of chromosome 11q, with various clinical manifestations. A post-term small for gestational age infant was born by normal vaginal delivery without trauma or vacuum extraction. On day 5, right parietotemporal scalp swelling developed, with petechiae on the right cheek and thrombocytopenia (platelets: 63,000/µL). A prominent forehead, wide-set eyes, short and upturned nose were noted. Karyotyping and microarray analysis demonstrated del(11)(q24q25), consistent with Jacobsen syndrome. Brain magnetic resonance imaging (MRI) revealed a huge cephalhematoma. The patient is scheduled to receive periodic evaluations for thrombocytopenia and heart, kidney, abdominal malformations, ophthalmologic and auditory problems. There are lots of newborns with cephalhematoma or petechiae after birth. Not all newborns with these symptoms need evaluations, but if they have these symptoms with suspect features or appearances, we need to go through further evaluations.