Single nucleotide polymorphisms (SNPs) in the gene encoding gamma glutamyl
hydrolase (GGH) associated with reduced GGH activity are disclosed. The
primary SNP is a change from a cytosine to a thymine at a position
corresponding to nucleotide 511 of Genbank sequence accession no. NM
003878. Methods and kits for detecting these SNPs are provided, along
with primers useful in detecting these SNP and for amplifying portions of
the GGH gene containing these SNPs.