Clinical Utility

Primary hyperoxaluria is an autosomal recessive disorder, which comprises three types depending on the causative genes: type 1 (AGXT), type 2 (GRHPR) and type 3 (HOGA1) (Hopp et al. 2015). 

AGXT has 11 coding exons that encode the liver peroxisomal enzyme alanine:glyoxylate-aminotransferase (AGT), which catalyzes the conversion of glyoxylate to glycine. Genetic defects of AGXT throughout the whole coding region include missense, nonsense, splicing site pathogenic variants, and small deletion/insertions (Human Gene Mutation Database). Exon-level large deletions involving AGXT have also been reported, but are relatively uncommon. 

GRHPR has 9 coding exons that encode the glyoxylate reductase/hydroxypyruvate reductase, which catalyzes the reduction of hydroxypyruvate to D-glycerate, the reduction of glyoxylate to glycolate and the oxidation of D-glycerate to hydroxypyruvate. Genetic defects of GRHPR throughout the whole coding region include missense, nonsense, splicing site pathogenic variants and small deletion/insertions (Human Gene Mutation Database). Exon-level large deletions and duplications involving GRHPR have not been reported. 

HOGA1 (formerly DHDPSL) has 7 coding exons that encode the 4-hydroxy-2-oxoglutarate aldolase, which catalyzes the final step in the metabolic pathway of hydroxyproline. Genetic defects of HOGA1 throughout the whole coding region include missense, nonsense, splicing site pathogenic variants and small deletion/insertions (Human Gene Mutation Database). Exon-level large deletions and duplications involving HOGA1 have not been reported.