Haplotype organisation of the <i>MTHFR</i> gene in the CEPH pedigrees.

<p>The haplotype block pattern was constructed using the Haploview program using data from the HapMap project. The number in each cell represents the LD parameter D' (x100). Each cell is colour graduated relative to the strength of LD between two markers. Red cells without numbers refer to pairs of SNPs in significant and maximum LD (i.e. D' = 1). Blue cells also represent pairs of SNPs with D' = 1, although in these case the observed LD levels are not statistically significant. The entire gene lies within a large haplotype block, within which two minor blocks can be identified. The rs numbers are the SNP ID in the NCBI SNP database. The marker rs1801131 (E429A) is located in haplotype block 1, marker rs2066472 (not shown) is located within haplotype block 2 and the markers A222V is located between these two haplotype blocks.