Preliminary evidence for ethnic differences in primary hyperoxaluria type 1 genotype.

Background: Primary hyperoxaluria type 1 (PH1) is caused by a deficiency of peroxisomal alanine:glyoxylate aminotransferase (AGT). In about one third of patients, enzymatically active AGT is synthesized but is mistargeted to mitochondria. There are more than 50 mutations identified in the gene for AGT. Four mutations, G170R, 33_34insC, F152I and I244T account for more than 50% of PH1 alleles. The question arose whether there are ethnic differences in PH1 genotype.

Methods: The published data on mutations in the AGT gene were examined with respect to recurrences and geographic or ethnic association. The mutations that have been found in at least 2 unrelated individuals were considered.

Results: Two common mutations, G170R and 33_34insC showed no obvious ethnic associations and have been found in a variety of populations. A third common PH1 mutation, I244T, has a strong association with people from a Spanish or North African background. A particularly high frequency among Canary Islands PH1 patients suggests a probable founder effect. Between these two extremes are a number of mutations that recur at low frequency within certain ethnic groups.

Conclusions: Ethnic associations of PH1 genotypes span a spectrum ranging from limited recurrences confined to a population group, to a probable founder effect.