Identification of a new single-nucleotide mutation on the hypoxanthine-guanine phosphoribosyltransferase gene from 983 cases with gout in Taiwan.

OBJECTIVE: The frequency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency within the gout-affected population in Taiwan was unclear. We evaluated its frequency and sought to identify a new genetic variation in a case with HPRT deficiency.
METHODS: From 2004 to 2005, a total of 983 patients with gout were followed among outpatients attending the Department of Rheumatology. Among these, 12 cases were suspected to have HPRT deficiency, and HPRT activity was examined by HPLC. In the index case found to have HPRT deficiency, genetic variation was analyzed by RT-PCR, direct sequencing, and SSCP.
RESULTS: Only a single case proved to have partial HPRT deficiency among 12 suspicious cases. Both cDNA and genomic DNA analysis identified a new mutation on exon 2 with T to G transition at cDNA base 93, resulting in a change from aspartic acid to glutamic acid at position 31. It was designated as HPRTChia-Yi, from our case's residence at Chia-Yi Hsein, Taiwan.
CONCLUSION: According to this hospital-based survey, HPRT deficiency is a rare trait in the Taiwanese gouty population. However, our index case with HPRT deficiency provided the first proven HPRT mutation in non-aboriginal Taiwanese patients with gout, which was different from a mutation previously found in aboriginal Taiwanese. Hence, in non-aboriginal Taiwanese gouty patients with HPRT deficiency, exon 2, rather than just exon 3, should be analyzed.