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Diagnostics
Original article
In vivo bioassay to test the pathogenicity of missense human AIP variants
  1. Elena Daniela Aflorei1,
  2. Benjamin Klapholz2,
  3. Chenghao Chen3,
  4. Serban Radian1,4,
  5. Anca Neluta Dragu1,3,
  6. Nina Moderau5,
  7. Chrisostomos Prodromou6,
  8. Paulo S Ribeiro5,
  9. Ralf Stanewsky3,7,
  10. Márta Korbonits1
  1. 1 Centre for Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London, UK
  2. 2 Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
  3. 3 Department of Cell and Developmental Biology, Division of Biosciences, Faculty of Life Sciences, University College London, London, UK
  4. 4 Department of Endocrinology, C.I. Parhon National Institute of Endocrinology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
  5. 5 Protein Dynamics and Cell Signalling Laboratory, Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, UK
  6. 6 Genome Damage and Stability Centre, University of Sussex, Brighton, UK
  7. 7 Institute of Neuro- and Behavioural Biology, Westfälische Wilhelms University, Münster, Germany
  1. Correspondence to Professor Márta Korbonits, Department of Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK; m.korbonits{at}qmul.ac.uk

Abstract

Background Heterozygous germline loss-of-function mutations in the aryl hydrocarbon receptor-interacting protein gene (AIP) predispose to childhood-onset pituitary tumours. The pathogenicity of missense variants may pose difficulties for genetic counselling and family follow-up.

Objective To develop an in vivo system to test the pathogenicity of human AIP mutations using the fruit fly Drosophila melanogaster.

Methods We generated a null mutant of the Drosophila AIP orthologue, CG1847, a gene located on the Xchromosome, which displayed lethality at larval stage in hemizygous knockout male mutants (CG1847exon1_3 ). We tested human missense variants of ‘unknown significance’, with ‘pathogenic’ variants as positive control.

Results We found that human AIP can functionally substitute for CG1847, as heterologous overexpression of human AIP rescued male CG1847exon1_3 lethality, while a truncated version of AIP did not restore viability. Flies harbouring patient-specific missense AIP variants (p.C238Y, p.I13N, p.W73R and p.G272D) failed to rescue CG1847exon1_3 mutants, while seven variants (p.R16H, p.Q164R, p.E293V, p.A299V, p.R304Q, p.R314W and p.R325Q) showed rescue, supporting a non-pathogenic role for these latter variants corresponding to prevalence and clinical data.

Conclusion Our in vivo model represents a valuable tool to characterise putative disease-causing human AIP variants and assist the genetic counselling and management of families carrying AIP variants.

  • AIP
  • drosophila melanogaster
  • FIPA
  • pathogenic genetic variant
  • pituitary adenoma

This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/

https://doi.org/10.1136/jmedgenet-2017-105191

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    Footnotes

    • Contributors EDA and MK prepared the manuscript for publication, in consultation with PSR and RS. All other authors had a role in contributing intellectually to redrafting the manuscript. All experiments were performed by EDA with support from BK, CC, NM and AND. SR supported the statistical analysis and assisted with drafting the manuscript. CP created the CG1847 protein theoretical model. All authors have seen and approved the final manuscript.

    • Funding Grant number MR/M018539/1 granted by Medical Research Council; WS733753 granted by Pfizer UK, November 2014 Early Career Grant awarded by Society for Endocrinology; #2011-5 awarded by William Harvey Research Foundation.

    • Competing interests None declared.

    • Patient consent Not required.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Not required as no additional unpublished data from the study.