Article Text
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
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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.