Mutational analysis of PHEX, FGF23, DMP1, SLC34A3 and CLCN5 in patients with hypophosphatemic rickets

Abstract

This study aimed to identify the underlying genetic mutation in patients with hypophosphatemic rickets (HR). Genomic DNA was analysed for mutations in PHEX, FGF23 and CLCN5 by polymerase chain reaction (PCR) followed by denaturing highperformance liquid chromatography (dHPLC). Bi-directional sequencing was performed in samples with deviating chromatographic profiles. DMP1 and SLC34A3 were sequenced, only. In addition, a multiplex ligation-dependent probe amplification (MLPA) analysis was performed to detect larger deletions/duplications in PHEX or FGF23. Familial cases accounted for 12 probands while 12 cases were sporadic. In 20 probands, mutations were detected in PHEX of which 12 were novel, and one novel frameshift mutation was found in DMP1. Three PHEX mutations were identified by the MLPA analysis only; that is, two large deletions and one duplication. No mutations were identified in FGF23, SLC34A3 or CLCN5. By the methods used, a disease causing mutation was identified in 83% of the familial and 92% of the sporadic cases, thereby in 88% of the tested probands. Genetic analysis performed in HR patients by PCR, dHPLC, sequencing and in addition by MLPA analysis revealed a high identification rate of gene mutations causing HR, including 12 novel PHEX and one novel DMP1 mutation.

Clinical and molecular heterogeneity in a large series of patients with hypophosphatemic rickets

“…We hypothesize that our high detection of deletions and duplications was obtained by the addition of the MLPA analysis. Similar results have been achieved in a recent study, where the MLPA analysis was performed [3]. In fact, all the mutations were identified by direct sequencing except for 4 deletions and 1 large duplication, which were detected by MLPA analysis.…”

“…Over the past decade, considerable advances have been made in unraveling the mechanism of phosphate homeostasis and the genetic abnormalities underlying the different forms of HR with the identification of several causal genes [3]. X-linked HR (XLHR), first described by Albright in 1937, is the most common form of HR, with a prevalence of 1 in 20,000 [4].…”

Clinical, hormonal, biochemical and genetic characteristics of 75 patients with hypophosphatemic rickets

“…По данным зарубежных исследований [15][16][17][18][19][20], в больших когортах пациентов с ГФР поломки гена PHEX определяются в 50-80% случаев. С. Gaucher и соавт.…”

Exome sequencing reveals a mutation in DMP1 in a family with familial sclerosing bone dysplasia

“…DMP1 acts as a transcriptional activator of osteoblast-specific genes such as alkaline phosphatase and osteocalcin, it moves out to the extracellular matrix during the osteoblast-osteocyte transition phase to promote mineralization and phosphate homeostasis [16]. To date only 7 mutations have been reported in the 6 exons of the DMP1 gene [4][5][6][7][8][9][10]; most of them are located in exon 6, suggesting that this area could be highly susceptible to genetic changes [17]. We report here a DMP1 mutation in 2 sisters born to consanguineous Lebanese parents.…”

“…In 2000, the principal regulator of phosphate metabolism, the fibroblast growth factor 23 (FGF23) was isolated and mutations of this gene were associated with the autosomal dominant form of the disease [3]. Additionally, pathogenic variants in two other genes the dentin matrix protein 1 (DMP1) [4][5][6][7][8][9][10] and the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) [11] were identified in patients with an extremely rare autosomal recessive HR (ARHR) type. The clinical, biochemical, and histomorphometric parameters found in ARHR are very similar to those observed in both X-linked and autosomal dominant HR and includes bowing of legs and growth failure during childhood, elevated FGF-23 and inappropriately normal 1-25-dihydroxyvitamin D (1-25(OH) 2 D) concentrations.…”