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Mikhail KA, VanSickle E, Rossetti LZ. Milder presentation of osteogenesis imperfecta type VIII due to compound heterozygosity for a predicted loss-of-function variant and novel missense variant in P3H1-further expansion of the phenotypic spectrum. Cold Spring Harb Mol Case Stud 2023; 9:mcs.a006260. [PMID: 36963805 PMCID: PMC10111797 DOI: 10.1101/mcs.a006260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/07/2023] [Indexed: 03/26/2023] Open
Abstract
Osteogenesis imperfecta (OI) is a heritable disorder of bone metabolism characterized by multiple fractures with minimal trauma. Autosomal recessive OI type VIII is associated with biallelic pathogenic variants in P3H1 and classically characterized by skeletal anomalies in addition to significant bone fragility, sometimes presenting with in utero fractures and/or neonatal lethality. P3H1 encodes a collagen prolyl hydroxylase that critically 3-hydroxylates proline residue 986 on the α chain of collagen types I and II to achieve proper folding and assembly of mature collagen and is present in a complex with CRTAP and CypB. Most individuals with OI type VIII have had biallelic predicted loss-of-function variants leading to reduced or absent levels of P3H1 mRNA. The reported missense variants have all fallen in the catalytic domain of the protein and are thought to be associated with a milder phenotype. Here, we describe an infant presenting with five long bone fractures in the first year of life found to have a novel missense variant in trans with a nonsense variant in P3H1 without any other bony anomalies on imaging. We hypothesize that missense variants in the catalytic domain of P3H1 lead to decreased but not absent hydroxylation of Pro986, with preserved KDEL retention signal and complex stability, causing an attenuated phenotype.
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Affiliation(s)
- Kristen A Mikhail
- Michigan State University College of Human Medicine, Grand Rapids, Michigan 49503, USA;
| | - Elizabeth VanSickle
- Division of Medical Genetics and Genomics, Corewell Health, Grand Rapids, Michigan 49503, USA
| | - Linda Z Rossetti
- Michigan State University College of Human Medicine, Grand Rapids, Michigan 49503, USA;
- Division of Medical Genetics and Genomics, Corewell Health, Grand Rapids, Michigan 49503, USA
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Garg B, Tomar N, Biswas A, Mehta N, Malhotra R. Understanding Musculoskeletal Disorders Through Next-Generation Sequencing. JBJS Rev 2022; 10:01874474-202204000-00001. [PMID: 35383688 DOI: 10.2106/jbjs.rvw.21.00165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
» An insight into musculoskeletal disorders through advancements in next-generation sequencing (NGS) promises to maximize benefits and improve outcomes through improved genetic diagnosis. » The primary use of whole exome sequencing (WES) for musculoskeletal disorders is to identify functionally relevant variants. » The current evidence has shown the superiority of NGS over conventional genotyping for identifying novel and rare genetic variants in patients with musculoskeletal disorders, due to its high throughput and low cost. » Genes identified in patients with scoliosis, osteoporosis, osteoarthritis, and osteogenesis imperfecta using NGS technologies are listed for further reference.
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Affiliation(s)
- Bhavuk Garg
- Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India
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Huang J, Fu J, Fu S, Yang L, Nie K, Duan C, Cheng J, Li Y, Lv H, Chen R, Liu L, Fu J. 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. Br J Ophthalmol 2018; 103:428-435. [PMID: 30366948 DOI: 10.1136/bjophthalmol-2018-312347] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 10/11/2018] [Accepted: 10/13/2018] [Indexed: 02/05/2023]
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.
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Affiliation(s)
- Junting Huang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Jiewen Fu
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, China
| | - Shangyi Fu
- The Honors College, University of Houston, Houston, Texas, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Lisha Yang
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, China
| | - Kailai Nie
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Chengxia Duan
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Jingliang Cheng
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, China
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Hongbin Lv
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Longqian Liu
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Junjiang Fu
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, China
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