Mutation analysis of four pedigrees affected with hypophosphatemic rickets through targeted next-generation sequencing

Objective: To detect potential mutations of PHEX gene in four pedigrees affected with hypophosphatemic rickets (HR) and provide prenatal diagnosis for a fetus at 13th gestational week.

Methods: The coding regions and exon/intron boundaries of PHEX, FGF23, DMP1, ENPP1, CLCN5 and SLC34A3 genes of the probands were analyzed by targeted next-generation sequencing (NGS). Suspected mutations were verified by Sanger sequencing among unaffected relatives and 200 unrelated healthy individuals. Deletions were confirmed by multiplex ligation-dependent probe amplification (MLPA) detection of probands, unaffected relatives and 20 unrelated healthy individuals. Prenatal diagnosis for a fetus with high risk was carried out through MLPA analysis.

Results: Four PHEX mutations were respectively detected in the pedigrees, which included c.850-3C>G, exon 11 deletion, exon 13 deletion and c.1753G>A (p.G585R). Among these, exon 11 deletion, exon 13 deletion and c.1753G>A (p.G585R) were novel mutations and not found among unaffected relatives and healthy controls. In pedigree 3, the same mutation was not found in the fetus.

Conclusions: Mutations of the PHEX gene probably underlies the disease among the four pedigrees. NGS combined with Sanger sequencing and/or MLPA detection can ensure accurate diagnosis for this disease.