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Diagnostic value of a combination of next-generation sequencing, chorioretinal imaging and metabolic analysis: lessons from a consanguineous Chinese family with gyrate atrophy of the choroid and retina stemming from a novel OAT variant
  1. Junting Huang1,
  2. Jiewen Fu2,
  3. Shangyi Fu3,4,
  4. Lisha Yang2,
  5. Kailai Nie1,
  6. Chengxia Duan5,
  7. Jingliang Cheng2,
  8. Yumei Li4,
  9. Hongbin Lv5,
  10. Rui Chen4,
  11. Longqian Liu1,
  12. Junjiang Fu2
  1. 1 Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
  2. 2 Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, China
  3. 3 The Honors College, University of Houston, Houston, Texas, USA
  4. 4 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
  5. 5 Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
  1. Correspondence to Dr Junjiang Fu, Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan 646000, China; fujunjiang{at}hotmail.com; LiuLongqian, Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu 15651, China; b.q15651{at}hotmail.com; Dr Rui Chen, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; ruichen{at}bcm.edu; Dr Hongbin Lv, Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; oculistlvhongbin{at}163.com

Abstract

Background/Aim Gyrate atrophy of the choroid and retina (GACR) is an extremely rare autosomal recessive inherited disorder characterised by progressive vision loss. To identify the disease-causing gene in a consanguineous Chinese pedigree with GACR, we aimed to accurately diagnose patients with GACR through a combination of next-generation sequencing (NGS) genetic diagnosis, clinical imaging and amino acid metabolic analysis.

Methods A consanguineous Chinese pedigree with GACR, including two patients, was recruited and a comprehensive ophthalmological evaluation was performed. DNA was extracted from a proband and her family members, and the sample from the proband was analysed using targeted NGS. Variants ‎detected by NGS were confirmed by Sanger sequencing and subjected to segregation analysis. Tandem mass spectrometry (MS/MS) was subsequently performed for metabolic assessment.

Results We identified a ‎novel, deleterious, homologous ornithine aminotransferase (OAT) variant, c.G248A: p.S83N, which contributes to ‎the progression of GACR in patients. Our results showed that the p.S83N autosomal recessive ‎variant of OAT is most likely ‎pathogenic, with changes in protein stability drastically decreasing functionality. MS/MS verified that ornithine levels in patients were significantly elevated.

Conclusions Recruitment of a third-degree first cousin consanguineous marriage family with GACR allowed us to identify a novel pathogenic OAT variant in the Chinese population, broadening the mutation spectrum. Our findings reported the diagnostic value of a combination of NGS, retinal imaging and metabolic analysis of consanguineous marriage pedigrees in low-income/middle-income and low-incidence countries, including China, and may help to guide accurate diagnosis and ‎treatment of this disease.

  • genetics
  • vision
  • diagnostic tests/investigation
  • biochemistry

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Footnotes

  • JH, JF and SF are Co-first authors.

  • Contributors JF, RC and HL: idea, project design and concept of the paper. JiF, JF, JC, SF and LY: DNA extraction, RNA extraction, PCR, RT-PCR, bioinformatic analysis, Sanger sequencing and data analysis. RC and YL: NGS analysis. JH, LL, HL, KN and CD: clinical patient recruitment and clinical assessment. JH: metabolic disorder analysis. JF and SF: manuscript writing. JF, LL and HL: manuscript revision.

  • Funding This work was supported in part by the National Natural Science Foundation of China (30371493, 31701087, 81172049 and 81672887), and the Joint Research Foundation of Luzhou City and Southwest Medical University (2018).

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval The study protocol was approved by the ethical committees of Southwest Medical University/Sichuan University (Luzhou, China), and all procedures adhered to the tenets of the Declaration of Helsinki.

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

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