Table 1. Description of genes and SNPs included in the analyses (the Northern California Childhood Leukemia Study, 1996-2002).

GENE, HUGO nomenclature [aliases, where appropriate]	Function of the protein encoded by the gene	Chr.	N. of SNPs selected for genotyping	SNPs excluded from analyses
CBS: cystathionine-beta-synthase [HIP4]	Catalyzes homocysteine to cystationine (first step of the transsulfuration pathway).	21	17	rs11203172* rs1672123* rs2124461* rs234709* rs8132811†
DHFR: dihydrofolate reductase	Converts dihydrofolate into tetrahydrofolate (methyl group shuttle required for the de novo synthesis of purines, thymidylic acid, and certain amino acids).	5	4	None
FOLH1: folate hydrolase (prostate-specific membrane antigen) 1 [PSM, FGCP, FOLH, GCP2, PSMA, Mgcp, GCPII, NAALAD1, NAALAdase]	Acts as a glutamate carboxypeptidase on different alternative substrates, including the nutrient folate; dysfunction may be associated with impaired intestinal absorption of dietary folates, resulting in hyperhomocysteinemia.	11	4	rs7113251‡
MTHFD1: methylenetetrahydrofolate dehydrogenase (NADP+ dependent) 1, methenyltetrahydrofolate cyclohydrolase, formyltetrahydrofolate synthetase [MTHFC, MTHFD]	Catalyzes three sequential reactions in the interconversion of 1.3 carbon derivatives of tetrahydrofolate (substrates for methionine, thymidylate, and de novo purine syntheses).	14	10	rs2236225†
MTHFR: 5,10-methylenetetrahydrofolate reductase (NADPH)	Catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate (cosubstrate for homocysteine remethylation to methionine).	1	10	rs4846040* rs7538516*
MTR: 5-methyltetrahydrofolate-homocysteine methyltransferase [MS, FLJ33168, FLJ43216, FLJ45386]	Catalyzes the final step in methionine biosynthesis.	1	4	None
MTRR: 5-methyltetrahydrofolate- homocysteine methyltransferase reductase [MSR, MGC129643]	Regenerates a functional 5-methyltetrahydrofolate- homocysteine methyltransferase via reductive methylation (which becomes inactive due to the oxidation of its cob(I)alamin cofactor).	5	18	rs1046012*
SHMT1: serine hydroxymethyltransferase 1 (soluble) [SHMT, CSHMT, MGC15229, MGC24556]	Catalyzes the reversible conversion of serine and tetrahydrofolate to glycine and 5,10-methylene tetrahydrofolate (this reaction provides one carbon units for synthesis of methionine, thymidylate, and purines in the cytoplasm).	17	5	None
SLC19A1: solute carrier family 19 (folate transporter), member 1 [CHMD, FOLT, IFC1, REFC, RFC1]	Main entry point of folate into cell; plays a role in maintaining intracellular concentrations of folate.	21	6	rs1050351* rs2838950* rs2838951*
TYMS: thymidylate synthetase [TS, TMS, Tsase, HsT422, MGC88736]	Catalyzes the methylation of deoxyuridylate to deoxythymidylate using 5,10-methylenetetrahydrofolate (methylene-THF) as a cofactor (this function maintains the dTMP (thymidine-5-prime monophosphate) pool critical for DNA replication and repair).	18	11	None

^*Genotyping failure

^†Hardy-Weinberg disequilibrium in both Hispanic and non-Hispanic controls (p<0.01)

^‡Minor allele frequency <5%