Mechanisms of inherited deficiencies of multiple UDP-glucuronosyltransferase isoforms in two patients with Crigler-Najjar syndrome, type I.

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Citation

Bosma PJ, Chowdhury JR, Huang TJ, Lahiri P, Elferink RP, Van Es HH, Lederstein M, Whitington PF, Jansen PL, Chowdhury NR

Mechanisms of inherited deficiencies of multiple UDP-glucuronosyltransferase isoforms in two patients with Crigler-Najjar syndrome, type I.

FASEB J. 1992 Jul;6(10):2859-63.

PubMed ID
1634050 [ View in PubMed
]
Abstract

Crigler-Najjar syndrome, type I (CN-I) is a potentially lethal disorder characterized by severe unconjugated hyperbilirubinemia resulting from a recessively inherited deficiency of hepatic UDP-glucuronosyl-transferase (UGT) activity toward bilirubin (B-UGT). Two forms of B-UGT exist in human liver. mRNAs for these two forms and that for another isoform with activity toward simple phenols (P-UGT) have unique 5' regions, but their 3' regions are identical. The three mRNA species are derived from a single locus; the unique 5' regions are encoded by single unique exons and the identical 3' regions consist of four consecutive exons that are shared by all three isoforms. In this paper, we determined genetic lesions in two CN-I patients with deficiency of hepatic B-UGT and P-UGT activities. In one patient, there was a C----T substitution in exon 4 (common region) predicting the substitution of a serine residue with a phenylalanine residue; this mutation was present in the identical region of B-UGT and P-UGT mRNAs. In the other patient, a C----T substitution in exon 2 (common region) of the B-UGT/P-UGT locus resulted in a premature stop codon. This exon (132 nt) was absent in heptic B-UGT and P-UGT mRNAs of this patient due to exon skipping during pre-mRNA processing. Sequence abnormality of three distinct mRNA species explains the abnormality of multiple UGT isoforms in these patients. Presence of identical abnormalities in the common regions of the three mRNAs is consistent with the finding that the common 3' regions of the two B-UGT mRNAs and the P-UGT mRNA are encoded by four shared exons.

DrugBank Data that Cites this Article

Polypeptides
NameUniProt ID
UDP-glucuronosyltransferase 1-1P22309Details
UDP-glucuronosyltransferase 1-4P22310Details