Identification of RNA splicing errors resulting in human ornithine transcarbamylase deficiency.

摘要: Abstract Ornithine transcarbamylase (OTC) is an X-linked, liver-specific enzyme that catalyzes the second step of urea cycle. In humans, inherited deficiency OTC in hemizygous affected males usually results severe ammonia intoxication and early death. To characterize mutations responsible for deficiency, we used PCR to amplify cDNAs prepared from patient livers which demonstrated no activity cross-reacting material on western blots. three seven cases, smaller than normal products were observed. Sequencing these revealed two missing exon 7 gene other was first 12 bp 5. genomic DNA patients one mutant had a T-to-C substitution 5' splice donor site intron 7. The A-to-G change third position It interesting both resulted skipping preceding rather inclusion some or all intron. mutant, A-to-T found 3' acceptor at end 4. Here, cryptic within 5 used. Northern blotting liver RNA (a) reduced, but significant, amounts mRNA who deleted (b) very little patients. We propose point mutations, result aberrant splicing pre-mRNAs, lead through either decreased efficiency export nucleus cytosol synthesis subunits are unstable rapidly degraded. speculate abnormal may represent relatively common mechanism pathogenesis this disease.