1. Epstein CJ. Down syndrome (Trisomy21). In: Scriver CR, Beaudet AL, Valle D, Sly WS, Childs B, Kinzler KW, Vogelstein B, editors. Metabolic and molecular bases of inherited diseases. New York: Vol. 1, McGraw Hill Medical Publishing Division; 2001. p. 1223–1256.
2. Patterson D, Graw S, Jones C. Demonstration by somatic cell genetics, of coordination of genes for two enzymes of purine synthesis assigned to human chromosome 21. Proc Natl Acad Sci USA. 1981;78:405–9.
3. Hard RG, Benkovic SJ, Van Keuren ML, Graw SL, Drabkin HA, Patterson D. Assignment of a third purine biosynthetic gene (Glycinamide ribonucleotide transformylase) to human chromosome 21. Am J Hum Genet. 1986;39:179–85.
4. Brodsky G, Barnes T, Bleskan J, Becker L, Cox M, Patterson D. The human GARS–AIRS–GART gene encodes two proteins which are differentially expressed during human brain development and temporally over-expressed in cerebellum of individuals with Down syndrome. Hum Mol Genet. 1997;6:2043–50.
5. Nelson DL, Cox MM. Biosynthesis of amino acids, nucleotides and related molecules. In: Lehninger Principles of Biochemistry. New York: Worth Publishers Macmillan Press Ltd; 2000. p. 849–52.