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Bernini A, Spiga O, Santucci A. Structure-Function Relationship of Homogentisate 1,2-dioxygenase: Understanding the Genotype-Phenotype Correlations in the Rare Genetic Disease Alkaptonuria. Curr Protein Pept Sci 2023; 24:380-392. [PMID: 36880186 DOI: 10.2174/1389203724666230307104135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/16/2023] [Accepted: 01/26/2023] [Indexed: 03/08/2023]
Abstract
Alkaptonuria (AKU), a rare genetic disorder, is characterized by the accumulation of homogentisic acid (HGA) in organs, which occurs because the homogentisate 1,2-dioxygenase (HGD) enzyme is not functional due to gene variants. Over time, HGA oxidation and accumulation cause the formation of the ochronotic pigment, a deposit that provokes tissue degeneration and organ malfunction. Here, we report a comprehensive review of the variants so far reported, the structural studies on the molecular consequences of protein stability and interaction, and molecular simulations for pharmacological chaperones as protein rescuers. Moreover, evidence accumulated so far in alkaptonuria research will be re-proposed as the bases for a precision medicine approach in a rare disease.
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Affiliation(s)
- Andrea Bernini
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Italy
| | - Ottavia Spiga
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Italy
| | - Annalisa Santucci
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Italy
- Centro Regionale Medicina di Precisione, Siena, Italy
- ARTES 4.0, Pontedera, Italy
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Taylor AM, Shepherd L. The potential of nitisinone for the treatment of alkaptonuria. Expert Opin Orphan Drugs 2019. [DOI: 10.1080/21678707.2019.1664899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Adam M Taylor
- Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Laura Shepherd
- Lancaster Medical School, Lancaster University, Lancaster, UK
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Khedr M, Judd S, Briggs MC, Hughes AT, Milan AM, Stewart RMK, Lock EA, Gallagher JA, Ranganath LR. Asymptomatic Corneal Keratopathy Secondary to Hypertyrosinaemia Following Low Dose Nitisinone and a Literature Review of Tyrosine Keratopathy in Alkaptonuria. JIMD Rep 2017; 40:31-37. [PMID: 28942493 DOI: 10.1007/8904_2017_62] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 08/17/2017] [Accepted: 09/04/2017] [Indexed: 12/13/2022] Open
Abstract
Nitisinone, although unapproved for use in alkaptonuria (AKU), is currently the only homogentisic acid lowering therapy with a potential to modify disease progression in AKU. Therefore, safe use of nitisinone off-label requires identifying and managing tyrosine keratopathy. A 22-year-old male with AKU commenced 2 mg daily nitisinone after full assessment. He was issued an alert card explaining potential ocular symptoms such as red eye, tearing, ocular pain and visual impairment and how to manage them. On his first and second annual follow-up visits to the National Alkaptonuria Centre (NAC), there was no corneal keratopathy on slit lamp examination. On his third follow-up annual visit to the NAC, he was found to have typical dendritiform corneal keratopathy in both eyes which was asymptomatic. Nitisinone was suspended until a repeat slit lamp examination, 2 weeks later, confirmed that the keratopathy had resolved. He recommenced nitisinone 2 mg daily with a stricter low protein diet. On his fourth annual follow-up visit to the NAC, a routine slit lamp examination showed mild corneal keratopathy in the left eye. This is despite him reporting no ocular symptoms. This case highlights the fact that corneal keratopathy can occur without symptoms and any monitoring plan with off-label use of nitisinone in AKU will need to take this possibility into account. This is also the first time that typical corneal keratopathy has been described with the use of low dose nitisinone in AKU without symptoms.
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Affiliation(s)
- M Khedr
- Department of Clinical Biochemistry and Metabolic Medicine, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK.
| | - S Judd
- Department of Nutrition and Dietetics, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK
| | - M C Briggs
- Department of Ophthalmology, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK
| | - A T Hughes
- Department of Clinical Biochemistry and Metabolic Medicine, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK.,Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, William Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
| | - A M Milan
- Department of Clinical Biochemistry and Metabolic Medicine, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK.,Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, William Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
| | - R M K Stewart
- Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, VIC, 3002, Australia.,Department of Eye and Vision Science, University of Liverpool, Liverpool, UK
| | - E A Lock
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - J A Gallagher
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, William Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
| | - L R Ranganath
- Department of Clinical Biochemistry and Metabolic Medicine, Liverpool Clinical Laboratories, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK.,Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, William Duncan Building, 6 West Derby Street, Liverpool, L7 8TX, UK
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A Founder Effect for the HGD G360R Mutation in Italy: Implications for a Regional Screening of Alkaptonuria. JIMD Rep 2016. [PMID: 26960557 DOI: 10.1007/8904_2016_534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] Open
Abstract
We sought to establish rapid and specific genotyping methods for G360R mutation and for seven tightly linked markers in the homogentisate dioxygenase gene to address the question of whether G360R is a mutational hot spot or the result of a founder effect, as it has been repeatedly found in alkaptonuric patients from a geographic isolate in Italy.For G360R and single nucleotide polymorphism genotyping, high-resolution melting analysis was performed. Microsatellites were analysed by multiplex PCR and capillary electrophoresis. To investigate the natural history of the G360R mutation, we genotyped markers in 52 controls and in 8 unrelated patients from the UK and USA, who also segregated the G360R mutation, and calculated its age using DMLE+2.3 software.A distinct G360R-bearing haplotype was identified in all patients of Caucasian descent. Estimated mutation age was 545 generations (95% credible set, 402-854), suggesting that G360R arose in an ancestor who lived 8,000-10,000 years BC. Archaeological, historical and demographic data support that a G360R carrier has settled the remote valley where present-day population might have a heterozygote frequency of at least 6%.Given the late health-threatening complications of alkaptonuria and a cure within reach, inhabitants of this isolate would benefit from screening and genetic counselling.
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