OBJECTIVETo 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.

METHODSThe 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.

RESULTSFour 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.

CONCLUSIONMutations 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.