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  • Clinical and subclinical findings in heterozygous ABCC6 carriers: results from a Belgian cohort and clinical practice guidelines

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Phenotypes
Original research
Clinical and subclinical findings in heterozygous ABCC6 carriers: results from a Belgian cohort and clinical practice guidelines
  1. Lukas Nollet1,2,
  2. Laurence Campens3,
  3. Julie De Zaeytijd4,
  4. Bart Leroy4,5,
  5. Dimitri Hemelsoet6,
  6. Paul J Coucke1,2,
  7. Olivier M Vanakker1,2
  1. 1 Center for Medical Genetics, University Hospital Ghent, Ghent, Belgium
  2. 2 Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
  3. 3 Department of Cardiology, University Hospital Ghent, Ghent, Belgium
  4. 4 Department of Ophthalmology, University Hospital Ghent, Ghent, Belgium
  5. 5 Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
  6. 6 Department of Neurology, University Hospital Ghent, Ghent, Belgium
  1. Correspondence to Dr Olivier M Vanakker, Center for Medical Genetics, University Hospital Ghent, Ghent, Belgium; Olivier.vanakker{at}ugent.be

Abstract

Background Biallelic pathogenic variants in the ATP-binding cassette subfamily C member 6 (ABCC6) gene cause pseudoxanthoma elasticum, a multisystemic ectopic calcification disorder, while heterozygous ABCC6 variants are associated with an increased risk of cardiovascular and cerebrovascular disease. As the prevalence of pathogenic ABCC6 variants in the general population is estimated at ~1%, identifying additional ABCC6-related (sub)clinical manifestations in heterozygous carriers is of the utmost importance to reduce this burden of disease. Here, we present a large Belgian cohort of heterozygous ABCC6 carriers with comprehensive clinical, biochemical and imaging data. Based on these results, we formulate clinical practice guidelines regarding screening, preventive measures and follow-up of ABCC6 carriers.

Methods The phenotype of 56 individuals carrying heterozygous pathogenic ABCC6 variants was assessed using clinical (eg, detailed ophthalmological examinations), biochemical, imaging (eg, cardiovascular and abdominal ultrasound) and genetic data. Clinical practice guidelines were then drawn up.

Results We found that ABCC6 heterozygosity is associated with distinct retinal alterations (‘comet-like’) (24%), high prevalence of hypercholesterolaemia (>75%) and diastolic dysfunction (33%), accelerated lower limb atherosclerosis and medial vascular disease, abdominal organ calcification (26%) and testicular microlithiasis (28%), though with highly variable expression.

Conclusion In this study, we delineated the multisystemic ABCC6 heterozygosity phenotype characterised by retinal alterations, aberrant lipid metabolism, diastolic dysfunction and increased vascular, abdominal and testicular calcifications. Our clinical practice guidelines aimed to improve early diagnosis, treatment and follow-up of ABCC6-related health problems.

  • phenotype
  • genetics
  • medical
  • clinical decision-making

Data availability statement

Data are available upon reasonable request.

https://doi.org/10.1136/jmedgenet-2020-107565

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    Data availability statement

    Data are available upon reasonable request.

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    Footnotes

    • Contributors Conceptualisation, methodology and visualisation: LN and OMV; data curation, formal analysis and writing (original draft preparation): LN; funding acquisition: LN, PJC and OMV; investigation: LN, LC, JDZ and BL; project administration and supervision: OMV; resources and validation: LC, JDZ, BL and DH; writing (review and editing): LC, JDZ, BL, DH, PJC and OMV.

    • Funding Figure 5 was created with Biorender.com.

    • Competing interests LN is a PhD fellow of the Research Foundation Flanders (FWO), Belgium (11F2121N), and was also supported by a Special Research Fund (BOF) grant from the Ghent University, Belgium (BOF19/DOC/253). OV and BL are senior clinical investigators of the FWO, Belgium.

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

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.