Splice-site mutations: A novel genetic mechanism of Crigler-Najjar syndrome type 1

Shailaja Gantla, Conny T M Bakker, Bishram Deocharan, Narsing R. Thummala, Jeffry Zweiner, Maarten Sinaasappel, Jayanta Roy-Chowdhury, Piter J. Bosma, Namita Roy Chowdhury

Research output: Contribution to journalArticle

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Abstract

Crigler-Najjar syndrome type 1 (CN-1) is a recessively inherited, potentially lethal disorder characterized by severe unconjugated hyperbilirubinemia resulting from deficiency of the hepatic enzyme bilirubin- UDP-glucuronosyltransferase. In all CN-1 patients studied, structural mutations in one of the five exons of the gene (UGT1A1) encoding the uridinediphosphoglucuronate glucuronosyltransferase (UGT) isoform bilirubin- UGT1 were implicated in the absence or inactivation of the enzyme. We report two patients in whom CN-1 is caused, instead, by mutations in the noncoding intronic region of the UGT1A1 gene. One patient (A) was homozygous for a G→C mutation at the splice-donor site in the intron, between exon 1 and exon 2. The other patient (B) was heterozygous for an A→G shift at the splice- acceptor site in intron 3, and in the second allele a premature translation- termination codon in exon 1 was identified. Bilirubin-UGT1 mRNA is difficult to obtain, since it is expressed in the liver only. To determine the effects of these splice-junction mutations, we amplified genomic DNA of the relevant splice junctions. The amplicons were expressed in COS-7 cells, and the expressed mRNAs were analyzed. In both cases, splice-site mutations led to the use of cryptic splice sites, with consequent deletions in the processed mRNA. This is the first report of intronic mutations causing CN-1 and of the determination of the consequences of these mutations on mRNA structure, by ex vivo expression.

Original languageEnglish (US)
Pages (from-to)585-592
Number of pages8
JournalAmerican Journal of Human Genetics
Volume62
Issue number3
DOIs
StatePublished - Mar 1998

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Crigler-Najjar Syndrome
Mutation
RNA Splice Sites
Exons
Messenger RNA
bilirubin glucuronoside glucuronosyltransferase
Bilirubin
Introns
Glucuronosyltransferase
Hyperbilirubinemia
Nonsense Codon
Liver
COS Cells
Enzymes
Genes
Protein Isoforms
Alleles

ASJC Scopus subject areas

  • Genetics

Cite this

Gantla, S., Bakker, C. T. M., Deocharan, B., Thummala, N. R., Zweiner, J., Sinaasappel, M., ... Chowdhury, N. R. (1998). Splice-site mutations: A novel genetic mechanism of Crigler-Najjar syndrome type 1. American Journal of Human Genetics, 62(3), 585-592. https://doi.org/10.1086/301756

Splice-site mutations : A novel genetic mechanism of Crigler-Najjar syndrome type 1. / Gantla, Shailaja; Bakker, Conny T M; Deocharan, Bishram; Thummala, Narsing R.; Zweiner, Jeffry; Sinaasappel, Maarten; Roy-Chowdhury, Jayanta; Bosma, Piter J.; Chowdhury, Namita Roy.

In: American Journal of Human Genetics, Vol. 62, No. 3, 03.1998, p. 585-592.

Research output: Contribution to journalArticle

Gantla, S, Bakker, CTM, Deocharan, B, Thummala, NR, Zweiner, J, Sinaasappel, M, Roy-Chowdhury, J, Bosma, PJ & Chowdhury, NR 1998, 'Splice-site mutations: A novel genetic mechanism of Crigler-Najjar syndrome type 1', American Journal of Human Genetics, vol. 62, no. 3, pp. 585-592. https://doi.org/10.1086/301756
Gantla S, Bakker CTM, Deocharan B, Thummala NR, Zweiner J, Sinaasappel M et al. Splice-site mutations: A novel genetic mechanism of Crigler-Najjar syndrome type 1. American Journal of Human Genetics. 1998 Mar;62(3):585-592. https://doi.org/10.1086/301756
Gantla, Shailaja ; Bakker, Conny T M ; Deocharan, Bishram ; Thummala, Narsing R. ; Zweiner, Jeffry ; Sinaasappel, Maarten ; Roy-Chowdhury, Jayanta ; Bosma, Piter J. ; Chowdhury, Namita Roy. / Splice-site mutations : A novel genetic mechanism of Crigler-Najjar syndrome type 1. In: American Journal of Human Genetics. 1998 ; Vol. 62, No. 3. pp. 585-592.
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