-
Journal of Cardiothoracic Surgery Jun 2024Alkaptonuria is a rare congenital metabolic disorder characterized by homogentisic acid accumulation in body cartilage and connective tissues due to a deficient...
BACKGROUND
Alkaptonuria is a rare congenital metabolic disorder characterized by homogentisic acid accumulation in body cartilage and connective tissues due to a deficient homogentisic acid dioxygenase enzyme. This disorder manifests in various clinical symptoms, including spondyloarthropathy, ocular and dermal pigmentation, genitourinary tract obstruction by ochronosis stones, and cardiovascular system involvement. Cardiac ochronosis is a rare manifestation of alkaptonuria that may present as aortic stenosis, sometimes accompanied by other cardiovascular complications.
CASE PRESENTATION
We report an unexpected case of ochronosis diagnosed during cardiac surgery. Due to the fragile, thin, and atheromatous nature of the ascending aorta in patients with ochronosis, we opted for a sutureless aortic valve replacement procedure. This approach appears to be more suitable for patients with ochronosis.
CONCLUSIONS
Although cardiac ochronosis is rare, surgeons should remain vigilant and consider the possibility of this condition when examining patients with aortic valve stenosis, paying close attention to the clinical manifestations of alkaptonuria.
Topics: Humans; Ochronosis; Aortic Valve Stenosis; Alkaptonuria; Heart Valve Prosthesis Implantation; Aortic Valve; Male; Sutureless Surgical Procedures; Female; Aged
PubMed: 38918861
DOI: 10.1186/s13019-024-02834-4 -
Cells Jun 2024Alkaptonuria (AKU) is a genetic disorder that affects connective tissues of several body compartments causing cartilage degeneration, tendon calcification, heart... (Review)
Review
Alkaptonuria (AKU) is a genetic disorder that affects connective tissues of several body compartments causing cartilage degeneration, tendon calcification, heart problems, and an invalidating, early-onset form of osteoarthritis. The molecular mechanisms underlying AKU involve homogentisic acid (HGA) accumulation in cells and tissues. HGA is highly reactive, able to modify several macromolecules, and activates different pathways, mostly involved in the onset and propagation of oxidative stress and inflammation, with consequences spreading from the microscopic to the macroscopic level leading to irreversible damage. Gaining a deeper understanding of AKU molecular mechanisms may provide novel possible therapeutical approaches to counteract disease progression. In this review, we first describe inflammation and oxidative stress in AKU and discuss similarities with other more common disorders. Then, we focus on HGA reactivity and AKU molecular mechanisms. We finally describe a multi-purpose digital platform, named ApreciseKUre, created to facilitate data collection, integration, and analysis of AKU-related data.
Topics: Alkaptonuria; Humans; Oxidative Stress; Homogentisic Acid; Inflammation; Animals
PubMed: 38920699
DOI: 10.3390/cells13121072 -
Joint replacement risk is markedly increased in alkaptonuria (AKU) in those with prior arthroplasty.Molecular Genetics and Metabolism... Sep 2024Increased homogentisic acid (HGA) in alkaptonuria (AKU) causes severe arthritis. Nitisinone reduces the production of HGA, but whether it also decreases arthroplasty was...
BACKGROUND
Increased homogentisic acid (HGA) in alkaptonuria (AKU) causes severe arthritis. Nitisinone reduces the production of HGA, but whether it also decreases arthroplasty was examined in 237 AKU patients.
PATIENTS AND METHODS
Patients attending the United Kingdom National Alkaptonuria Centre (NAC) and the Suitability of Nitisinone in Alkaptonuria 2 (SONIA 2) study were studied. Assessments included questionnaires eliciting details of arthroplasty. Nitisinone was administered from baseline, 2 mg in the NAC and 10 mg in SONIA 2. In SONIA 2, subgroups consisted of those with baseline arthroplasty on and not on nitisinone (BR + N+, BR + N-), as well as those without baseline arthroplasty on and not on nitisinone (BR-N+, BR-N-).
RESULTS
In the SONIA2 subgroups, new joint replacement (JR) probabilities after baseline were significantly different (BR + N+, BR + N-, BR-N+, BR-N-) (χ = 23.3, < 0.001); mean (SD) was 3.8 (0.1) years in BR-N-, 3.7 (0.1) years in BR-N+, 3.4 (0.3) years in BR + N-, and 3.0 (0.3) years in BR + N+. Further, the BR + N- showed more JR than the BR-N- subgroup ( < 0.01), while BR + N+ similarly showed more JR than the BR-N+ subgroup ( < 0.001).In the NAC, the BR- group had a mean age of 51.6 7.0) years at baseline but 57.7 (8.7) years at final follow up during nitisinone therapy and showed only 7 incident JR. The BR+ group had an age at baseline of 57.4 (8.5) years and had undergone 94 JRs at baseline.
CONCLUSION
The incidence of arthroplasty was earlier and more frequent after the first JR and was not affected by nitisinone.
PubMed: 38846518
DOI: 10.1016/j.ymgmr.2024.101097 -
Journal of Inherited Metabolic Disease Mar 2024Altered activity of specific enzymes in phenylalanine-tyrosine (phe-tyr) metabolism results in incomplete breakdown of various metabolite substrates in this pathway....
Altered activity of specific enzymes in phenylalanine-tyrosine (phe-tyr) metabolism results in incomplete breakdown of various metabolite substrates in this pathway. Increased biofluid concentration and tissue accumulation of the phe-tyr pathway metabolite homogentisic acid (HGA) is central to pathophysiology in the inherited disorder alkaptonuria (AKU). Accumulation of metabolites upstream of HGA, including tyrosine, occurs in patients on nitisinone, a licenced drug for AKU and hereditary tyrosinaemia type 1, which inhibits the enzyme responsible for HGA production. The aim of this study was to investigate the phe-tyr metabolite content of key biofluids and tissues in AKU mice on and off nitisinone to gain new insights into the biodistribution of metabolites in these altered metabolic states. The data show for the first time that HGA is present in bile in AKU (mean [±SD] = 1003[±410] μmol/L; nitisinone-treated AKU mean [±SD] = 45[±23] μmol/L). Biliary tyrosine, 3(4-hydroxyphenyl)pyruvic acid (HPPA) and 3(4-hydroxyphenyl)lactic acid (HPLA) are also increased on nitisinone. Urine was confirmed as the dominant elimination route of HGA in untreated AKU, but with indication of biliary excretion. These data provide new insights into pathways of phe-tyr metabolite biodistribution and metabolism, showing for the first time that hepatobiliary excretion contributes to the total pool of metabolites in this pathway. Our data suggest that biliary elimination of organic acids and other metabolites may play an underappreciated role in disorders of metabolism. We propose that our finding of approximately 3.8 times greater urinary HGA excretion in AKU mice compared with patients is one reason for the lack of extensive tissue ochronosis in the AKU mouse model.
PubMed: 38487984
DOI: 10.1002/jimd.12728 -
Annals of Medicine and Surgery (2012) May 2024Alkaptonuria is an autosomal extremely rare recessive metabolic disorder with incidence reported to occur as 1:100 000-1:250 000 live births worldwide. This rare...
INTRODUCTION
Alkaptonuria is an autosomal extremely rare recessive metabolic disorder with incidence reported to occur as 1:100 000-1:250 000 live births worldwide. This rare metabolic disorder is characterized by the accumulation of homogentisic acid due to a deficiency in homogentisic acid 1,2 dioxygenase. Homogentisic acid subsequently oxidizes and accumulates in the connective tissue. The knee is the most significant peripheral joint to be affected by the disorder. The authors present the first case of ochronotic arthropathy in Syria.
CASE PRESENTATION
A 46-year-old male presented with bilateral pain in the knees. the pain was affecting his day-to-day activities, and not responding to conservative management. Anteroposterior standing radiographs demonstrated extensive degenerative disease. Intraoperatively, the diagnosis was done after noticing that the quadriceps tendon and the articular cartilage of the femur, tibia, and patella were blackened during cemented total knee replacement of the knee.
CONCLUSION
Ochronotic arthropathy should be kept in mind in middle age patients with severe osteoarthritis to not be surprised by the rare alkaptonuria diagnosis if arthroplasty was indicated.
PubMed: 38694340
DOI: 10.1097/MS9.0000000000001775 -
European Heart Journal. Case Reports Feb 2024Alkaptonuria is a rare metabolic disease that causes an increase in homogentisic acid (HGA) due to a lack of enzymatic activity. Commonly, accumulation of HGA presents...
BACKGROUND
Alkaptonuria is a rare metabolic disease that causes an increase in homogentisic acid (HGA) due to a lack of enzymatic activity. Commonly, accumulation of HGA presents with dark discoloration of skin and other tissues, also known as ochronosis. Additionally, alkaptonuria can result in other clinical manifestations, including arthritis and cardiac disease. This case highlights alkaptonuria-related cardiac disease and challenges that cardiac surgery teams may face when treating this patient population.
CASE SUMMARY
A 62-year-old male with a history of alkaptonuria, Hodgkin's lymphoma treated with chemoradiation, hypertension, and hyperlipidaemia originally presented with shortness of breath in the setting of known cardiac disease. Cardiac work-up demonstrated aortic stenosis, mitral stenosis, and multivessel coronary artery disease requiring aortic valve replacement, mitral valve replacement, and coronary artery bypass grafting. During the operation, significant discoloration of tissue was observed. This correlated with areas of severe calcification, which was noted throughout both valves. Extensive debridement was required prior to proceeding to valve replacements. Additionally, near-infrared spectroscopy failed to provide accurate measurements of cerebral oxygenation.
DISCUSSION
Alkaptonuria is correlated with cardiovascular disease, particularly valvular disease. Intraoperatively, these patients may exhibit noticeable discoloration and severe calcification of various tissues. Additionally, traditional infrared-based methods of cerebral oxygenation monitoring may not be reliable; however, other options of cerebral monitoring may be feasible. With proper pre-operative planning, however, patients with alkaptonuria may safely undergo cardiac surgery.
PubMed: 38405194
DOI: 10.1093/ehjcr/ytae076 -
Journal of Cutaneous Pathology Sep 2023
Topics: Humans; Argyria; Elastic Tissue; Ochronosis; Alkaptonuria
PubMed: 37316955
DOI: 10.1111/cup.14476 -
Indian Journal of Dermatology,... Mar 2024
PubMed: 38595002
DOI: 10.25259/IJDVL_890_2023 -
Journal of Orthopaedic Case Reports Feb 2024Alkaptonuria is a rare autosomal recessive disorder caused by the defective metabolism of homogentisic acid, with a rare course and remained undetected even until...
INTRODUCTION
Alkaptonuria is a rare autosomal recessive disorder caused by the defective metabolism of homogentisic acid, with a rare course and remained undetected even until adulthood. Ochronotic arthropathy is one of the manifestations of alkaptonuria, predominantly affecting weight bearing joints such as spine, hip, and knee. Total joint arthroplasty is treatment of choice in end-stage arthritis of hip and knee. Owing to the rarity of the disease, limited data is available in literature regarding surgical challenges and long-term functional outcomes.
CASE REPORT
Herein, we present a case of 43-year-old male with ochronotic arthropathy of bilateral hip, right knee, and bilateral elbow joints with involvement of spine, who was incidentally diagnosed with ochronotic arthropathy intraoperatively and underwent sequential arthroplasty for right hip followed by right knee and left hip over a period of 10 years. At 11 years' follow-up, the patient has full mobility with no loosening of implants.
CONCLUSION
The long-term results of total joint arthroplasty in ochronotic arthropathy are good. Surgeon should be aware of the difficulty in soft tissue balancing and possible complications in the ochronotic arthropathy and require a conscientious approach to avoid complications.
PubMed: 38420236
DOI: 10.13107/jocr.2024.v14.i02.4224 -
Journal of Orthopaedic Case Reports Jun 2024Alkaptonuria is a rare autosomal recessive genetic disorder found in 2-5/million live births. It results in dark brown pigmentation of connective tissues including...
INTRODUCTION
Alkaptonuria is a rare autosomal recessive genetic disorder found in 2-5/million live births. It results in dark brown pigmentation of connective tissues including cartilage and joint capsule that can often lead to arthropathy of large joints. However, bone fractures are unusual. This article describes a fracture neck of the femur in a patient with undiagnosed alkaptonuria managed at a rural center.
CASE REPORT
A 60-year-old daily wage laborer with previously pain-free hips presented with sudden onset pain in the left hip while walking with no prior history of trauma. Radiographs showed a displaced fracture of the neck of the left femur. She underwent Left hip hemiarthroplasty. Intraoperatively, her soft-tissue including the joint capsule and the femoral head had dark brown pigmentation. Postoperatively, her urine was tested and the same turned black supporting the clinical diagnosis of alkaptonuria. At her 1-year follow-up, she had a painless, stable, and mobile hip.
CONCLUSION
We report a rare and unique case of neck of femur fracture in a patient with alkaptonuria treated with hemiarthroplasty in a resource-limited hospital in rural India. It is essential to consider the possibility of this condition when we come across a patient with an atypical fracture presentation. This article also presents an overview of alkaptonuria with a discussion on etiopathogenesis, clinical presentation, diagnosis, and management.
PubMed: 38910974
DOI: 10.13107/jocr.2024.v14.i06.4508