Characterization of genomic DNA, mRNA and enzyme protein in cases of HPRT-deficiency.

1. Immunological quantitation of the HPRT proteins, together with DNA and RNA studies have defined further the heterogeneous nature of HPRT-deficiency in our patients. 2. These studies have dictated possible approaches for further characterisation of the HPRT enzyme in our patients. In the two Lesch-Nyhan patients, both the protein and the usual cDNA approach would appear difficult. 3. A BamHI polymorphism has been detected in Patient A. 4. Sequence data confirmed the creation of this BamHI site by a single C----T transition at position 602 in the coding sequence. 5. Sequencing of other patients is proceeding and use is being made of the Polymerase Chain Reaction (PCR)10 for amplification of specific segments of HPRT coding sequence.