HEREDITARY HYPOPHOSPHATEMIC RICKETS WITH HYPERCALCIURIA (CASE REPORT)

Abstract

Hereditary hypophosphatemic rickets with hypercalciuria is a very rare autosomal recessive disease, pathogenic base of which is phosphorus reabsorption disorder in proximal nephron with following development of hypophsphatemia, hypercalciuria calcitriol level increase, decrease of parathyroid hormone, osteopenia and bony deformity. This disease refers to hypophosphatemic rickets, due to mutations in the SLC34A3 gene that encodes the sodium-phosphate cotransporter NaPi-IIc, which is responsible for phosphorus reabsorption in the proximal nephron. In this article, we present a clinical observation for a child with atypical manifestations of hereditary hypophosphatemic rickets with hypercalciuria. The clinical examination showed non constant hypophosphatemia, normal values of maximum tubular phosphate transport, absence of calcitriol serum concentrations increase, rachitic changes and bone mineral disorders during a long period of observation. It didn’t allow clinically to identify one of the variants of hypophosphatemic rickets in a child. The diagnosis was confirmed by the results of complete exome sequencing which revealed previously undescribed compound heterozygous mutation c.1382G> A (p.Trp461Ter) in exon 13 and p.1094-3C> T in intron 10 of the SLC34A3 gene. A correct diagnosis allowed us to reconsider the approaches of the treatment: in hereditary rickets recommended only phosphorus supplementation and prescription of vitamin D due to its increased endogenous production.