An annotation of the distribution of single nucleotide substitutions identified in the open reading frame of GAD1.The approximate positions with respect to intron-exon of the open reading frame structure are illustrated. These were determined by sequencing of the probands in this study, from published data and from the NCBI collated database of SNPs. The letters refer to the SNPs listed in Table 4. Upper case letters refer to SNPs in the cDNA and lower case letters indicate SNPs in the genomic DNA. A: G(36)C, B: G(210)A, C: G(253)C, D: T(315)C, E: A(407)G, F: C(696)T, G: C(1506)T, H: C(1575)T, i: T(1625)G, J: C(1654)T, k: A(1659)G, l: G(1799)A, m: C(1899)A.