Purine nucleotides can be synthesized in two ways: ab initio synthesis and remedial synthesis. Remedial synthesis refers to the synthesis of AMP, GMP and imp by PRPP (phosphoribosyl pyrophosphate) using a, G and I, and under the catalysis of aprt (adenine phosphoribosyltransferase) and HGPRT (hypoxanthine guanine phosphoribosyltransferase).

Some tissues and organs, such as brain and bone marrow, lack the enzyme system of ab initio purine nucleotide synthesis, and can only be used for remedial synthesis. Children with complete HGPRT deficiency due to genetic defects are characterized by self disfigurement or Lesch Nyhan syndrome.