Duplication in the hypoxanthine phosphoribosyl-transferase gene caused by Alu-Alu recombination in a patient with Lesch Nyhan syndrome.

We have determined the structure, at the nucleotide sequence level, of a duplication in the hprt gene in a patient with Lesch-Nyhan syndrome (LN). The duplication extends over exons 7 and 8 and approximately 1.8 kb of the surrounding hprt sequence. The duplication junction is localized within two Alu sequences and has apparently been generated by unequal homologous recombination. This is the second reported case of a partial duplication of the hprt gene in an LN patient, and the first that involves an Alu-Alu recombination.