Abstract
Virtually complete deficiency of hypoxanthine phosphoribosyltransferase (HPRT) results in the Lesch-Nyhan syndrome. Partial deficiency of HPRT results in gout. We have previously sequenced the normal enzyme and documented the amino acid substitution in four mutant forms of the enzyme. We have undertaken a molecular genetic survey of cell lines derived from HPRT-deficient patients in order to define specific mutations for which protein sequencing is impractical or impossible. Lymphoblasts derived from 17 patients deficient in HPRT (9 with the Lesch-Nyhan syndrome; 8 with partial HPRT deficiency) were studied. Northern blot analysis of mRNA derived from these cell lines was used to determine the molecular size and relative concentrations of message. Three cell lines had no detectable HPRT mRNA. In the remaining cell lines, all but one exhibited normal molecular size (1.6 Kb); the exception had a molecular weight of 1.8 Kb. Relative concentrations of mRNA ranged from slightly diminished in 3, normal in II and increased in 3. To more completely define the molecular abnormality, we have generated a cDNA library derived from mRNA obtained from one patient's cultured B-lymphoblasts. From this library, a mutant HPRT cDNA was cloned. This cDNA is 1200 base pairs in length and has restriction maps with Hae III, Hinc II and Hind III identical to normal HPRT-cDNA. This approach provides a direct method for defining the mutation in all mRNA+ HPRT- subjects. From this survey we conclude that analysis of mutant HPRT at the DNA and mRNA level provides a powerful tool to define specific mutations.
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Davidson, B., Palella, T., Wilson, J. et al. A MOLECULAR SURVEY OF HPRT DEFICIENCY: 48. Pediatr Res 19, 751 (1985). https://doi.org/10.1203/00006450-198507000-00068
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DOI: https://doi.org/10.1203/00006450-198507000-00068