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Hum Mutat. 2018 Mar;39(3):378-382. doi: 10.1002/humu.23383. Epub 2018 Jan 24.

A noncoding variant in GANAB explains isolated polycystic liver disease (PCLD) in a large family.

Author information

1
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
2
Department of Genetics, Yale University School of Medicine, New Haven, Connecticut.
3
Department of Medicine, Columbia University, New York, New York.
4
Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota.

Abstract

Expanded mutation detection and novel gene discovery for isolated polycystic liver disease (PCLD) are necessary as 50% of cases do not have identified mutations in the seven published disease genes. We investigated a family with five affected siblings for which no loss-of-function variants were identified by whole exome sequencing analysis. SNP genotyping and linkage analysis narrowed the candidate regions to ∼8% of the genome, which included two published PCLD genes in close proximity to each other, GANAB and LRP5. Based on these findings, we re-evaluated the exome sequencing data and identified a novel intronic nine base pair deletion in the vicinity of the GANAB exon 24 splice donor that had initially been discarded by the sequence analysis pipelines. We used a minigene assay to show that this deletion leads to skipping of exon 24 in cell lines and primary human cholangiocytes. These findings prompt genomic evaluation beyond the coding region to enhance mutation detection in PCLD and to avoid premature implication of other genes in linkage disequilibrium.

KEYWORDS:

GANAB; LRP5; minigene; polycystic liver disease; splice assay

PMID:
29243290
PMCID:
PMC5805583
[Available on 2019-03-01]
DOI:
10.1002/humu.23383

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