Two Novel HOGA1 Splicing Mutations Identified in a Chinese Patient with Primary Hyperoxaluria Type 3

Twenty-six HOGA1 mutations have been reported in primary hyperoxaluria (PH) type 3 (PH3) patients with c.700 + 5G>T accounting for about 50% of the total alleles. However, PH3 has never been described in Asians.

A Chinese child with early-onset nephrolithiasis was suspected of having PH. We searched for AGXT, GRHPR and HOGA1 gene mutations in this patient and his parents. All coding regions, including intron-exon boundaries, were analyzed using PCR followed by direct sequence analysis.

Two heterozygous mutations not previously described in the literature about HOGA1 were identified (compound heterozygous). One mutation was a successive 2 bp substitution at the last nucleotide of exon 6 and at the first nucleotide of intron 6, respectively (c.834_834 + 1GG>TT), while the other one was a guanine to adenine substitution of the last nucleotide of exon 6 (c.834G>A). Direct sequencing analysis failed to find these mutations in 100 unrelated healthy subjects and the functional role on splicing of both variants found in this study was confirmed by a minigene assay based on the pSPL3 exon trapping vector. In addition, we found a SNP in this family (c.715G>A, p.V239I). There were no mutations detected in AGXT and GRHPR.

Two novel HOGA1 mutations were identified in association with PH3. This is the first description and investigation on mutant gene analysis of PH3 in an Asian.