Missense mutations in the WD40 domain of AHI1 cause non-syndromic retinitis pigmentosa

Thanh-Minh T Nguyen, Sarah Hull, Ronald Roepman, L Ingeborgh van den Born, Machteld M Oud, Erik de Vrieze, Lisette Hetterschijt, Stef J F Letteboer, Sylvia E C van Beersum, Ellen A Blokland, Helger G Yntema, Frans P M Cremers, Paul A van der Zwaag, Gavin Arno, Erwin van Wijk, Andrew R Webster, Lonneke Haer-Wigman

Research output: Contribution to journalArticleResearchpeer-review

Abstract

BACKGROUND: Recent findings suggesting that Abelson helper integration site 1 (AHI1) is involved in non-syndromic retinal disease have been debated, as the functional significance of identified missense variants was uncertain. We assessed whether AHI1 variants cause non-syndromic retinitis pigmentosa (RP).

METHODS: Exome sequencing was performed in three probands with RP. The effects of the identified missense variants in AHI1 were predicted by three-dimensional structure homology modelling. Ciliary parameters were evaluated in patient's fibroblasts, and recombinant mutant proteins were expressed in ciliated retinal pigmented epithelium cells.

RESULTS: In the three patients with RP, three sets of compound heterozygous variants were detected in AHI1 (c.2174G>A; p.Trp725* and c.2258A>T; p.Asp753Val, c.660delC; p.Ser221Glnfs*10 and c.2090C>T; p.Pro697Leu, c.2087A>G; p.His696Arg and c.2429C>T; p.Pro810Leu). All four missense variants were present in the conserved WD40 domain of Jouberin, the ciliary protein encoded by AHI1, with variable predicted implications for the domain structure. No significant changes in the percentage of ciliated cells, nor in cilium length or intraflagellar transport were detected. However, expression of mutant recombinant Jouberin in ciliated cells showed a significantly decreased enrichment at the ciliary base.

CONCLUSIONS: This report confirms that mutations in AHI1 can underlie autosomal recessive RP. Moreover, it structurally and functionally validates the effect of the RP-associated AHI1 variants on protein function, thus proposing a new genotype-phenotype correlation for AHI1 mutation associated retinal ciliopathies.

Original languageEnglish
Pages (from-to)624-632
Number of pages9
JournalJournal of Medical Genetics
Volume54
Issue number9
DOIs
Publication statusPublished - Sep 2017

Keywords

  • Abnormalities, Multiple/genetics
  • Adaptor Proteins, Signal Transducing/chemistry
  • Adaptor Proteins, Vesicular Transport
  • Adult
  • Cerebellum/abnormalities
  • Eye Abnormalities/genetics
  • Female
  • Humans
  • Kidney Diseases, Cystic/genetics
  • Male
  • Middle Aged
  • Mutation, Missense
  • Pedigree
  • Protein Domains/genetics
  • Retina/abnormalities
  • Retinitis Pigmentosa/genetics

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