- Alkaptonuric Ochronosis and the Failure of Regional Cerebral Tissue Oxygen Saturation Monitoring by Two Different Near-infrared Spectroscopy Devices. [Journal Article]
- JCJ Cardiothorac Vasc Anesth 2017 Dec 29
- The role of the clinician in the multi-omics era: are you ready? [Journal Article]
- JIJ Inherit Metab Dis 2018 Jan 23
- Since Garrod's first description of alkaptonuria in 1902, and newborn screening for phenylketonuria introduced in the 1960s, P4 medicine (preventive, predictive, personalized, and participatory) has ...
Since Garrod's first description of alkaptonuria in 1902, and newborn screening for phenylketonuria introduced in the 1960s, P4 medicine (preventive, predictive, personalized, and participatory) has been a reality for the clinician serving patients with inherited metabolic diseases. The era of high-throughput technologies promises to accelerate its scale dramatically. Genomics, transcriptomics, epigenomics, proteomics, glycomics, metabolomics, and lipidomics offer an amazing opportunity for holistic investigation and contextual pathophysiologic understanding of inherited metabolic diseases for precise diagnosis and tailored treatment. While each of the -omics technologies is important to systems biology, some are more mature than others. Exome sequencing is emerging as a reimbursed test in clinics around the world, and untargeted metabolomics has the potential to serve as a single biochemical testing platform. The challenge lies in the integration and cautious interpretation of these big data, with translation into clinically meaningful information and/or action for our patients. A daunting but exciting task for the clinician; we provide clinical cases to illustrate the importance of his/her role as the connector between physicians, laboratory experts and researchers in the basic, computer, and clinical sciences. Open collaborations, data sharing, functional assays, and model organisms play a key role in the validation of -omics discoveries. Having all the right expertise at the table when discussing the diagnostic approach and individualized management plan according to the information yielded by -omics investigations (e.g., actionable mutations, novel therapeutic interventions), is the stepping stone of P4 medicine. Patient participation and the adjustment of the medical team's plan to his/her and the family's wishes most certainly is the capstone. Are you ready?
- Mechanisms of enhanced osteoclastogenesis in Alkaptonuria. [Journal Article]
- AJAm J Pathol 2018 Jan 15
- Alkaptonuria (AKU) is a rare disorder characterized by the deficiency of the enzyme homogentisate 1,2-dioxygenase and consequent homogentisate accumulation, which leads to progressive and severe oste...
Alkaptonuria (AKU) is a rare disorder characterized by the deficiency of the enzyme homogentisate 1,2-dioxygenase and consequent homogentisate accumulation, which leads to progressive and severe osteoarthopathy starting from the second decade of life. Thus, in AKU patients bone involvement represents an important clinical issue, which we investigated. Serum levels of RANKL, osteoprotegerin, sclerostin, DKK1, and bone remodeling markers were measured in nine AKU patients (two children and seven adults) and 22 controls, together with lumbar spine bone mineral density (LS-BMD) and femoral-BMD. In the two AKU children the average of LS-BMD and femoral-BMD Z-scores were within the normal range, but reduced with respect to the controls. Otherwise, in the adult AKU patients LS-BMD T-score were inside the normal range, but femoral-BMD T-score reached osteopenic levels. Consistently, in AKU adults higher RANKL and CTX and lower osteoprotegerin levels were observed than controls. Otherwise, spontaneous osteoclastogenesis was already evident in peripheral blood mononuclear cell cultures from AKU children together with a high percentage of circulating osteoclast precursors. Osteoclastogenesis was sustained by the high levels of TNFα, RANK, RANKL, and LIGHT. In conclusion, the altered osteoclastogenesis was observed already in AKU children despite the absence of evident injury. Thus, a preventive approach in young patients, targeting osteoclast activity, may prevent the macroscopic bone disease which appears in adult AKU.
- Assessment of the Effect of Once Daily Nitisinone Therapy on 24-h Urinary Metadrenalines and 5-Hydroxyindole Acetic Acid Excretion in Patients with Alkaptonuria After 4 Weeks of Treatment. [Journal Article]
- JRJIMD Rep 2017 Nov 17
- CONCLUSIONS: This study shows that catecholamine and serotonin metabolism is altered by treatment with nitisinone.
- Calcaneal Avulsion of an Ochronotic Achilles Tendon: A Case Report. [Journal Article]
- JFJ Foot Ankle Surg 2018 Jan - Feb; 57(1):179-183
- Alkaptonuria is a hereditary disorder of phenylalanine and tyrosine, with an incidence of approximately 1/200,000 to 1/1,000,000. Ochronosis is the accumulation of homogentisic acid and its metabolit...
Alkaptonuria is a hereditary disorder of phenylalanine and tyrosine, with an incidence of approximately 1/200,000 to 1/1,000,000. Ochronosis is the accumulation of homogentisic acid and its metabolites in connective tissues such as the tendons, cartilage, and skin. In the present case study, a 50-year-old male presented with a nontraumatic calcaneal avulsion without a previous diagnosis of ochronosis. To the best of our knowledge, little information has been reported of this pathology in the Achilles tendon and the surgical management.
- Woman in black: the cardiac ochronosis with severe aortic valve stenosis. [Journal Article]
- EJEur J Cardiothorac Surg 2017 Oct 28
- Asymptomatic Corneal Keratopathy Secondary to Hypertyrosinaemia Following Low Dose Nitisinone and a Literature Review of Tyrosine Keratopathy in Alkaptonuria. [Journal Article]
- JRJIMD Rep 2017 Sep 24
- 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 n...
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.
- Nitisinone-Induced Keratopathy in Alkaptonuria: A Challenging Diagnosis Despite Clinical Suspicion. [Journal Article]
- JRJIMD Rep 2017 Sep 07
- Alkaptonuria is a rare disorder of amino acid metabolism that causes premature large joint and spine arthropathy and cardiac valvular disease. It is characterised by elevated levels of homogentisic a...
Alkaptonuria is a rare disorder of amino acid metabolism that causes premature large joint and spine arthropathy and cardiac valvular disease. It is characterised by elevated levels of homogentisic acid. Nitisinone (NTBC) is a benzoylcyclohexane-1,3-dione that reversibly inhibits the activity of the enzymatic step immediately prior to homogentisate dioxygenase, hence reducing the production of homogentisic acid. Thus it is thought that nitisinone might be a treatment for alkaptonuria. A side effect of NTBC therapy is elevation of plasma tyrosine levels in a manner analogous to tyrosinemia type 2, another related condition which causes a painful palmoplantar hyperkeratosis and eye pathology described as conjunctivitis and herpetic-like corneal ulceration. There are only two previous reports of NTBC causing eye symptoms in patients with alkaptonuria. Here we provide further evidence of this side effect of treatment and its resolution with cessation of NTBC. Repeat challenges with NTBC provoked symptoms, but introducing a low protein diet with low dose NTBC was successful in controlling plasma tyrosine levels and the patient remained free of symptoms when levels were below 600 μmol/L. Our patient was remarkable for the low dose of NTBC that precipitated symptoms (as little as 0.5 mg daily), and for the difficulty in proving its causation despite clinical suspicion.
- Arthroscopic diagnosis and treatment of shoulder ochronotic arthropathy - A case report. [Journal Article]
- JCJ Clin Orthop Trauma 2017; 8(Suppl 1):S80-S83
- Alkaptonuria is a rare inherited metabolic disorder, caused by the deficiency of homogentisate 1,2 dioxygenase enzyme. The three major features of alkaptonuria are the presence of homogentisic acid i...
Alkaptonuria is a rare inherited metabolic disorder, caused by the deficiency of homogentisate 1,2 dioxygenase enzyme. The three major features of alkaptonuria are the presence of homogentisic acid in urine, ochronosis (bluish-black pigmentation in connective tissue) and arthritis of the spine and large joints. We present a 48 years old female presented with pain, restriction of movements of right shoulder. Arthroscopy was suggestive of ochronotic arthropathy. The definitive diagnosis of ochronosis was subsequently confirmed by laboratory and pathologic evaluation.
New Search Next
- Toward a generalized computational workflow for exploiting transient pockets as new targets for small molecule stabilizers: Application to the homogentisate 1,2-dioxygenase mutants at the base of rare disease Alkaptonuria. [Journal Article]
- CBComput Biol Chem 2017; 70:133-141
- Alkaptonuria (AKU) is an inborn error of metabolism where mutation of homogentisate 1,2-dioxygenase (HGD) gene leads to a deleterious or misfolded product with subsequent loss of enzymatic degradatio...
Alkaptonuria (AKU) is an inborn error of metabolism where mutation of homogentisate 1,2-dioxygenase (HGD) gene leads to a deleterious or misfolded product with subsequent loss of enzymatic degradation of homogentisic acid (HGA) whose accumulation in tissues causes ochronosis and degeneration. There is no licensed therapy for AKU. Many missense mutations have been individuated as responsible for quaternary structure disruption of the native hexameric HGD. A new approach to the treatment of AKU is here proposed aiming to totally or partially rescue enzyme activity by targeting of HGD with pharmacological chaperones, i.e. small molecules helping structural stability. Co-factor pockets from oligomeric proteins have already been successfully exploited as targets for such a strategy, but no similar sites are present at HGD surface; hence, transient pockets are here proposed as a target for pharmacological chaperones. Transient pockets are detected along the molecular dynamics trajectory of the protein and filtered down to a set of suitable sites for structural stabilization by mean of biochemical and pharmacological criteria. The result is a computational workflow relevant to other inborn errors of metabolism requiring rescue of oligomeric, misfolded enzymes.