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Journal of Clinical Laboratory Analysis Nov 2023Homogentisic acid (HGA) is excreted in excessive amounts in the urine of patients with alkaptonuria, which is a hereditary metabolic disorder of phenylalanine and...
OBJECTIVE
Homogentisic acid (HGA) is excreted in excessive amounts in the urine of patients with alkaptonuria, which is a hereditary metabolic disorder of phenylalanine and tyrosine. Therefore, the detection of HGA in urine is useful for the diagnosis of alkaptonuria. To evaluate the detection of HGA, we confirmed the color shift of HGA solutions and analyzed them by electrospray ionization mass spectrometry (ESI-MS).
METHODS
We observed the color change of the HGA solutions under different pH conditions (pH 6.0, 7.0, and 8.0) and examined the influences of adding potassium hydroxide (KOH) and ascorbic acid (AA) to the HGA solutions. Then, we analyzed the chemical reaction in HGA solutions using ESI-MS.
RESULTS
The HGA solution at pH 8.0 became brown after incubation at room temperature for 24 h and became darker brown with the addition of KOH; however, HGA solutions at pH 6.0 and 7.0 showed no color changes. The brown color change of the HGA solution at pH 8.0 was also inhibited by AA. Moreover, all HGA sample solutions showed the deprotonated molecular ion peak at m/z 167.035 in the negative ion mode after incubation at room temperature for 24 h and with the addition of KOH and AA.
CONCLUSION
We identified the molecular ion of HGA in all sample solutions by ESI-MS, regardless of different pH conditions, color changes, or the presence of AA. These results suggest that spectral analysis by ESI-MS is suitable for the detection of HGA and the diagnosis of alkaptonuria.
Topics: Humans; Alkaptonuria; Spectrometry, Mass, Electrospray Ionization; Homogentisic Acid; Hydroxides; Ascorbic Acid
PubMed: 37877521
DOI: 10.1002/jcla.24976 -
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 -
Metabolites Aug 2022Nitisinone (NIT) causes tyrosinaemia and corneal keratopathy (KP), especially in men. However, the adaptation within the phenylalanine (PHE)/tyrosine (TYR) catabolic...
Comparing the Phenylalanine/Tyrosine Pathway and Related Factors between Keratopathy and No-Keratopathy Groups as Well as between Genders in Alkaptonuria during Nitisinone Treatment.
Nitisinone (NIT) causes tyrosinaemia and corneal keratopathy (KP), especially in men. However, the adaptation within the phenylalanine (PHE)/tyrosine (TYR) catabolic pathway during KP is not understood. The objective of this study is to assess potential differences in the PHE/TYR pathway during KP and the influence of gender in NIT-induced tyrosinaemia in alkaptonuria (AKU). Samples of serum and 24 h urine collected from patients treated with NIT during a 4-year randomized study in NIT vs. no-treatment controls (SONIA 2; Suitability Of Nitisinone In Alkaptonuria 2; EudraCT no. 2013-001633-41) at months 3 (V2), 12 (V3), 24 (V4), 36 (V5) and 48 (V6) were included in these analyses. Homogentisic acid (HGA), TYR, PHE, hydroxyphenylpyruvate (HPPA), hydroxyphenyllactate (HPLA) and sNIT were analysed at all time-points in serum and urine in the NIT-group. All statistical analyses were post hoc. Keratopathy occurred in 10 out of 69 AKU patients, eight of them male. Thirty-five sampling points (serum and 24 h urine) were analysed in patients experiencing KP and 272 in those with no-KP (NKP) during NIT therapy. The KP group had a lower HPLA/TYR ratio and a higher TYR/PHE ratio compared with the NKP group (p < 0.05 for both). There were 24, 45, 100 and 207 sampling points (serum and 24 h urine) in the NIT group which were pre-NIT female, pre-NIT male, NIT female and NIT male, respectively. The PHE/TYR ratio and the HPLA/TYR ratio were lower in males (p < 0.001 and p < 0.01, respectively). In the KP group and in the male group during NIT therapy, adaptive responses to minimise TYR formation were impaired compared to NKP group and females, respectively.
PubMed: 36005644
DOI: 10.3390/metabo12080772 -
Journal of Inherited Metabolic Disease Mar 2020Alkaptonuria (AKU) is caused by homogentisate 1,2-dioxygenase deficiency that leads to homogentisic acid (HGA) accumulation, ochronosis and severe osteoarthropathy.... (Observational Study)
Observational Study
Alkaptonuria (AKU) is caused by homogentisate 1,2-dioxygenase deficiency that leads to homogentisic acid (HGA) accumulation, ochronosis and severe osteoarthropathy. Recently, nitisinone treatment, which blocks HGA formation, has been effective in AKU patients. However, a consequence of nitisinone is elevated tyrosine that can cause keratopathy. The effect of tyrosine and phenylalanine dietary restriction was investigated in nitisinone-treated AKU mice, and in an observational study of dietary intervention in AKU patients. Nitisinone-treated AKU mice were fed tyrosine/phenylalanine-free and phenylalanine-free diets with phenylalanine supplementation in drinking water. Tyrosine metabolites were measured pre-nitisinone, post-nitisinone, and after dietary restriction. Subsequently an observational study was undertaken in 10 patients attending the National Alkaptonuria Centre (NAC), with tyrosine >700 μmol/L who had been advised to restrict dietary protein intake and where necessary, to use tyrosine/phenylalanine-free amino acid supplements. Elevated tyrosine (813 μmol/L) was significantly reduced in nitisinone-treated AKU mice fed a tyrosine/phenylalanine-free diet in a dose responsive manner. At 3 days of restriction, tyrosine was 389.3, 274.8, and 144.3 μmol/L with decreasing phenylalanine doses. In contrast, tyrosine was not effectively reduced in mice by a phenylalanine-free diet; at 3 days tyrosine was 757.3, 530.2, and 656.2 μmol/L, with no dose response to phenylalanine supplementation. In NAC patients, tyrosine was significantly reduced (P = .002) when restricting dietary protein alone, and when combined with tyrosine/phenylalanine-free amino acid supplementation; 4 out of 10 patients achieved tyrosine <700 μmol/L. Tyrosine/phenylalanine dietary restriction significantly reduced nitisinone-induced tyrosinemia in mice, with phenylalanine restriction alone proving ineffective. Similarly, protein restriction significantly reduced circulating tyrosine in AKU patients.
Topics: Alkaptonuria; Animals; Cyclohexanones; Diet, Protein-Restricted; Female; Humans; Male; Mice; Nitrobenzoates; Phenylalanine; Tyrosine; Tyrosinemias
PubMed: 31503358
DOI: 10.1002/jimd.12172 -
Cureus Oct 2023Alkaptonuria is a rare genetic disorder characterized by the excessive production of homogentisic acid, leading to the formation and deposition of pigment polymers...
Alkaptonuria is a rare genetic disorder characterized by the excessive production of homogentisic acid, leading to the formation and deposition of pigment polymers throughout the body. It is extremely rare, affecting only around one in 100,000 individuals. Despite the normal life expectancy, it can cause severe morbidities. Alkaptonuria is typically managed supportively with pain medication, dietary modifications, and surgical interventions, which are considered to be the gold standard of therapy. Here we present a case of a 33-year-old male with no previous medical or surgical history who presented with severe acute back pain radiating to the left leg. Genetic testing confirmed a homozygous pathogenic variant for alkaptonuria. This case highlights the challenges in diagnosing alkaptonuria, emphasizing the significance of early detection, and clinical evaluation for improved outcomes. Furthermore, it underscores the need to consider alkaptonuria as a multidimensional disease, necessitating further research to enhance our understanding and develop effective management. Therefore, this study serves as an opportunity for future trials and studies aimed at digging deeper into the intricacies of alkaptonuria to increase our understanding and establish comprehensive management plans for affected individuals.
PubMed: 37937039
DOI: 10.7759/cureus.46644 -
BioMed Research International 2021Metabolic disorder alkaptonuria is an autosomal recessive disorder caused by mutations in the gene, and a deficiency HGD enzyme activity results in an accumulation of...
BACKGROUND
Metabolic disorder alkaptonuria is an autosomal recessive disorder caused by mutations in the gene, and a deficiency HGD enzyme activity results in an accumulation of homogentisic acid (HGA), ochronosis, and destruction of connective tissue.
METHODS
We clinically evaluated 18 alkaptonuria patients (age range, 3 to 60 years) from four unrelated families. Furthermore, 11 out of 18 alkaptonuria patients and 7 unaffected members were enrolled for molecular investigations by utilizing Sanger sequencing to identify variants of the 14 exons of gene.
RESULTS
We found that the seven patients from the 4 unrelated families carried a recurrent pathogenic missense variant (c.365C>T, p. Ala122Val) in exon 6 of gene. The variant was fully segregated with the disease in affected family members while the other unaffected family members were heterozygous carriers for this variant. Additionally, the clinical features were fully predicted with alkaptonuria disorder.
CONCLUSION
In this study, we confirmed that the most common variants in Jordanian AKU patients was c.365C>T, p. Ala122Val in exon 6 of gene. Additionally, we correlated the clinical and genetic features of AKU patients at various ages (3-60 years).
Topics: Adolescent; Adult; Alkaptonuria; Child; Child, Preschool; Exons; Family Health; Female; Founder Effect; Genes, Recessive; Genetic Variation; Heterozygote; Homogentisate 1,2-Dioxygenase; Homogentisic Acid; Humans; Jordan; Male; Middle Aged; Mutation, Missense; Ochronosis; Oligonucleotides; Pedigree; Sequence Analysis, DNA; Young Adult
PubMed: 34235214
DOI: 10.1155/2021/1515641 -
JIMD Reports May 2020Alkaptonuria (AKU) is an ultrarare and multifaceted disease characterized by the absence of functional homogentisate 1,2-dioxygenase activity, the enzyme responsible for...
BACKGROUND
Alkaptonuria (AKU) is an ultrarare and multifaceted disease characterized by the absence of functional homogentisate 1,2-dioxygenase activity, the enzyme responsible for breakdown of homogentisic acid-a tyrosine-degradation product. The presymptomatic phase of the disease makes diagnosis difficult, with many patients unidentified or diagnosed late in life.
OBJECTIVE
To date, no study has analyzed the perceived impact of different symptoms or the experiences of individuals through the patient journey in the context of AKU. This study aimed to examine patients' perceptions of AKU symptoms and their impact on quality of life as well as patients' experiences of being diagnosed and living with the disease.
METHODS
Data for this study were collected using a quantitative self-report questionnaire administered online to people with AKU.
RESULTS
Data from 45 participants indicate that symptoms with the highest impact for patients are those related to pain and ruptures, disability and inability to perform normal routines, emotional/mental health issues, and heart complications. Findings also revealed significant delays in contact with healthcare services and time to diagnosis. Furthermore, patients reported difficulty in receiving information about AKU, treatment and care, and long-term disease management support.
CONCLUSIONS
Time to diagnosis and care of AKU is significantly delayed. Symptoms of AKU with the highest impact on quality of life for patients are those related to pain and disability and the inability to perform normal routines. Bridging any gaps between patients with AKU and healthcare professionals through education could help improve patients' experiences with AKU through the patient journey.
PubMed: 32395411
DOI: 10.1002/jmd2.12101 -
International Journal of Molecular... Jul 2023Nitisinone has been approved for treatment of alkaptonuria (AKU). Non-invasive biomarkers of joint tissue remodelling could aid in understanding the molecular changes in... (Randomized Controlled Trial)
Randomized Controlled Trial
Nitisinone has been approved for treatment of alkaptonuria (AKU). Non-invasive biomarkers of joint tissue remodelling could aid in understanding the molecular changes in AKU pathogenesis and how these can be affected by treatment. Serological and urinary biomarkers of type I collagen and II collagen in AKU were investigated in patients enrolled in the randomized SONIA 2 (NCT01916382) clinical study at baseline and yearly until the end of the study (Year 4). The trajectories of the biomarkers over time were observed. After treatment with nitisinone, the biomarkers of type I collagen remodelling increased at Year 1 (19% and 40% increase in CTX-I and PRO-C1, respectively), which was potentially reflected in the higher degree of mobility seen following treatment. The biomarkers of type II collagen remodelling decreased over time in the nitisinone group: C2M showed a 9.7% decline at Year 1, and levels then remained stable over the following visits; CTX-II showed a 26% decline at Year 3 and 4 in the nitisinone-treated patients. Nitisinone treatment induced changes in biomarkers of bone and cartilage remodelling. These biomarkers can aid patient management and deepen our knowledge of the molecular mechanisms of this rare disease.
Topics: Humans; Alkaptonuria; Biomarkers; Cartilage; Collagen Type I
PubMed: 37446173
DOI: 10.3390/ijms241310996 -
Endocrine Regulations Jan 2023Alkaptonuria (AKU, OMIM, No. 203500) is a rare, slow-progressing, irreversible, multisystemic disease resulting from a deficiency of the homogentisate 1,2-dioxygenase...
Alkaptonuria (AKU, OMIM, No. 203500) is a rare, slow-progressing, irreversible, multisystemic disease resulting from a deficiency of the homogentisate 1,2-dioxygenase enzyme, which leads to the accumulation of homogentisic acid (HGA) and subsequent deposition as pigment in connective tissues called ochronosis. As a result, severe arthropathy of large joints and spondyloarthropathy with frequent fractures, ligament ruptures, and osteoporosis develops in AKU patients. Since 2020, the first-time treatment with nitisinone has become available in the European Union. Nitisinone significantly reduces HGA production and arrests ochronosis in AKU patients. However, blocking of the tyrosine metabolic pathway by the drug leads to tyrosine plasma and tissue concentrations increase. The nitisinone-induced hypertyrosinemia can lead to the development of corneal keratopathy, and once it develops, the treatment needs to be interrupted. A decrease in overall protein intake reduces the risk of the keratopathy during nitisinone-induced hypertyrosinemia in AKU patients. The low-protein diet is not only poorly tolerated by patients, but over longer periods, leads to a severe muscle loss and weight gain due to increased energy intake from carbohydrates and fats. Therefore, the development of novel nutritional approaches is required to prevent the adverse events due to nitisinone-induced hypertyrosinemia and the negative impact on skeletal muscle metabolism in AKU patients.
Topics: Humans; Alkaptonuria; Ochronosis; Tyrosinemias; Tyrosine; Homogentisic Acid
PubMed: 36966367
DOI: 10.2478/enr-2023-0008 -
Cells Nov 2022Nitisinone (NTBC) was recently approved to treat alkaptonuria (AKU), but there is no information on its impact on oxidative stress and inflammation, which are observed...
Nitisinone (NTBC) was recently approved to treat alkaptonuria (AKU), but there is no information on its impact on oxidative stress and inflammation, which are observed in AKU. Therefore, serum samples collected during the clinical studies SONIA1 (40 AKU patients) and SONIA2 (138 AKU patients) were tested for Serum Amyloid A (SAA), CRP and IL-8 by ELISA; Advanced Oxidation Protein Products (AOPP) by spectrophotometry; and protein carbonyls by Western blot. Our results show that NTBC had no significant effects on the tested markers except for a slight but statistically significant effect for NTBC, but not for the combination of time and NTBC, on SAA levels in SONIA2 patients. Notably, the majority of SONIA2 patients presented with SAA > 10 mg/L, and 30 patients in the control group (43.5%) and 40 patients (58.0%) in the NTBC-treated group showed persistently elevated SAA > 10 mg/L at each visit during SONIA2. Higher serum SAA correlated with lower quality of life and higher morbidity. Despite no quantitative differences in AOPP, the preliminary analysis of protein carbonyls highlighted patterns that deserve further investigation. Overall, our results suggest that NTBC cannot control the sub-clinical inflammation due to increased SAA observed in AKU, which is also a risk factor for developing secondary amyloidosis.
Topics: Humans; Alkaptonuria; Advanced Oxidation Protein Products; Quality of Life; Biomarkers; Serum Amyloid A Protein; Inflammation; Oxidative Stress
PubMed: 36429096
DOI: 10.3390/cells11223668