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Ochronosis, the musculoskeletal manifestation of alkaptonuria, is known to lead to degenerative changes of the spine and weight-bearing joints. Symptoms related to degeneration of tendons or ligaments with spontaneous ruptures have not previously been reported. Three patients are described with four spontaneous ruptures of either the patellar tendon or tendo Achillis as the first symptom of alkaptonuria.
Alkaptonuria is an extremely rare, autosomal recessive disorder in which the metabolic enzyme homogentisic acid oxidase is deficient. A common sequelae is the subsequent accumulation of homogentisic acid in collagenous tissues, such as the sclera, nose and ear lobes. The blue-black pigmentation found in patients with alkaptonuria is called ochronosis. Another ocular sign includes amber-colored oil globulation within Bowmans membrane of the cornea.
Thirty members of Family C, which included cases of alkaptonuria and ochronosis, were investigated by means of HLA typing and homogentistic acid determination. The antigen HLA B27 was found in one of the two members of the first generation, in all eight members of the second generation, and in 15 of the 21 members of the third generation. Eight of 10 subjects suffering from alkaptonuria, with or without ochronotic arthropathy or spondylosis, had B27. The gene for B27 is not the gene determining homogentisic acid oxydase synthesis but this study suggests that it may be associated or linked to it.
Non-enzymatic oxidation in alkaline media of homogentisinic acid, excreted with urine in alkaptonuria, involved free radical mechanism. The oxidative process was accompanied by production of superoxide anion O2- and required metal cations. Free radical destruction of cells and biopolymers via O2- or homogentisinic acid semiquinone appears to be one of pathogenetic mechanisms responsible for impairment of connective tissue structures in patients with alkaptonuria.
Patients with alkaptonuria lack homogentisate 1,2-dioxygenase leading to retention of homogentistic acid (HGA) in body fluids and eventually to tissue deposition of oxidation products, giving rise to the clinical picture of ochronosis. Ascorbic acid is a known inhibitor of the enzyme which catalyses the oxidation of homogentisic acid (HGA) to the polymer with affinity for collagen and was used in the treatment of three siblings with alkaptonuria. Ascorbic acid 500 mg bid was administered for 12 months. Two of the siblings tolerated the treatment, and in one the symptoms improved, whereas in the other they worsened. Plasma and urinary levels of HGA were monitored with a new HPLC method. Ascorbic acid is not effective in the treatment of symptomatic ochronosis.
A 59-year-old woman with previously documented alkaptonuria was examined for extensive ochronosis of recent onset. The cause of the extensive skin pigmentations were thought to be secondary to decreased renal clearance of homogentisic acid because of a decline in the patient's renal function. If extensive or rapidly progressive skin pigmentation is noted in a patient with alkaptonuria, then evaluation of the patient's renal status should be done because unrelated renal disease has been reported in patients with severe ochronosis.
We describe a study of a boy with neonatal severe primary hyperparathyroidism (NSPHP) and alkaptonuria born to related parents of Turkish origin. The clinical and chemical courses (e.g. of mineral metabolism, of urinary excretion of amino acids and collagen metabolites) in response to various therapeutic approaches including total parathyroidectomy (PTX) are reported. Urinary excretion of calcium was unusually low before and immediately after PTX, and later during an inadvertent vitamin D intoxication. It corresponded to values typical for patients with familial hypocalciuric hypercalcemia (FHH), an autosomal dominant disorder. Both parents and one sibling had episodes of hypercalcemia with inappropriately high parathormone levels; in the father there was also relative hypocalciuria consistent with FHH. On the basis of the genetic and pathophysiologic data reported here, we speculate that homozygosity for the 'FHH-gene' is the cause of the life-threatening manifestation of NSPHP, whereas heterozygosity for the same gene leads to FHH, by comparison a mild disorder. The association of the two very rare recessively transmitted disorders, alkaptonuria and NSPHP, is unique; close linkage of the two genes, one coding for homogentisic acid oxidase, the other for the unknown gene product defective in NSPHP, can be suspected.
We report the case of a 64 year old woman treated for 10 years by DOPA for Parkinson's disease and displaying brown urine. Homogentisic acid was found in urine, establishing the diagnosis of alkaptonuria. Clinical and radiological studies demonstrated ochronosis and ochronotic arthropathy, blue pigmentation of ear cartilage and calcification of the intervertebral lumbar disc giving the classical "inverted spine". Interrelation between this metabolic abnormality and Parkinson's disease is discussed. The recent cloning and mapping of the human gene for alkaptonuria to chromosome 3q should bring some clarification among relationships between these two diseases.
Spinal involvement in alkaptonuria is common. Patients usually present in the third or fourth decade with spondylosis or acute intervertebral disc prolapse. Alkaptonuria with root canal stenosis has however hitherto not been reported. We wish to report one such patient.
Alkaptonuria is an uncommon tyrosine metabolism disorder. Deficit of homogentisic acid oxidase leads to the elimination of large amounts of homogentisic acid in the urine with accumulation of homogentisic acid oxidized pigment in the connective tissue (ochronosis). The ultimate evolution of ochronosis is degenerative arthritis. The clinical case reported is a 57-year old male diagnosed with alkaptonuria in an early stage of the connective tissue disease who comes to the clinic due to a lower urinary obstructive syndrome secondary to benign prostate hyperplasia but is diagnosed with giant prostate lithiasis. The patient undergoes retropubic adenomectomy with lithiasis removal and re-implantation of ectopic ureter from a dual left excretory system. Clinical evolution is completely successful. The rarity of the case calls for circulation and revision of the clinical and therapeutical aspects of this entity.
Alkaptonuria (aku), an inborn error of metabolism caused by the loss of homogentisate 1,2-dioxygenase (HGD), has been described in a mouse model created by ethylnitrosourea mutagenesis but the mutation in these mice has not previously been identified. We used RT-PCR to amplify the Hgd cDNA from Hgd(aku)/Hgd(aku) mice. Two products shorter than the wild-type product were amplified. Restriction mapping and DNA sequencing were then used to identify the Hgd(aku) mouse mutation, found to be a single base change in a splice donor consensus sequence, causing exon skipping and frame-shifted products. This base change allowed us to create a non-radioactive genotyping assay for this allele.
For several years the Clinical Genetics Research Laboratory at Martin, Czechoslovakia, has been studying alkaptonuria (AU) in the northern part of the District of Trencín in Slovakia. These affected individuals are part of a group of 103 alkaptonurics originated mostly in the mountainous parts of Slovakia. We report results of pedigree analyses; population and affected-family biochemical urine screening; estimation of inbreeding coefficient, of exogamy rate and of average marital distance and of calculation of the frequency of the AU allele, and of homozygotes and heterozygotes in this portion of the Trencín District. Twelve homozygotes were found, but seven originated from a single hamlet in which a founder effect - genetic drift and inbreeding - are thought to account for the high prevalence of AU.
Crucial for the establishment and development of biochemical genetics as a self-standing discipline was Beadle and Tatum's choice of Neurospora crassa as experimental organism some 60 years ago. Although Garrod's insights on biochemical genetics and his astonishingly modern concepts of biochemical individuality and susceptibility to disease had been ignored by their contemporaries, Beadle acknowledged on several occasions how close Garrod had come to the "one-gene-one-enzyme" hypothesis. In an unexpected turn of events, several genes involved in human inborn errors of metabolism, including the gene for Garrod's favorite disease, alkaptonuria, have been characterized by exploitation of the experimental advantages of another mold, Aspergillus nidulans, which shares with N. crassa the experimental advantages that prompted pioneers of biochemical genetics to use them: rapid growth, facile genetic manipulation, and an environment (the composition of the growth medium) that can be manipulated à la carte.
Alkaptonuria (AKU) is an autosomal recessive disorder caused by the deficiency of homogentisate 1,2 dioxygenase (HGO) activity. AKU shows a very low prevalence (1:100,000-250,000) in most ethnic groups. One notable exception is in Slovakia, where the incidence of AKU rises to 1:19,000. This high incidence is difficult to explain by a classical founder effect, because as many as 10 different AKU mutations have been identified in this relatively small country. We have determined the allelic associations of 11 HGO intragenic polymorphisms for 44 AKU chromosomes from 20 Slovak pedigrees. These data were compared to the HGO haplotype data available in our laboratory for >80 AKU chromosomes from different European and non-European countries. The results show that common European AKU chromosomes have had only a marginal contribution to the Slovak AKU gene pool. Six of the ten Slovak AKU mutations, including the prevalent G152fs, G161R, G270R, and P370fs mutations, most likely originated in Slovakia. Data available for 17 Slovak AKU pedigrees indicate that most of the AKU chromosomes have their origins in a single very small region in the Carpathian mountains, in the northwestern part of the country. Since all six Slovak AKU mutations are associated with HGO mutational hot spots, we suggest that an increased mutation rate at the HGO gene is responsible for the clustering of AKU mutations in such a small geographical region.
We report the case of a 62 year old man diagnosed of alkaptonuria who was referred to our department to undergo bone scintigraphy for polyarthralgia. The patient had a history of pain in lumbar and thoracic spine, right shoulder and left knee. Bone scintigraphy showed multiple joint disease with increased uptake in both shoulders, knees and spine. Higher uptake stood out in painful right shoulder and left knee joints. Ochronotic arthropathy that is developed in alkaptonuric patients is a degenerative joint disease. X-ray studies in this patient showed marked degenerative arthrosis in knees and shoulders, without more intense involvement in the symptomatic joints. Lumbar spine X-rays showed intervertebral disk calcification with disk collapse and fusion of the vertebral bodies with relative sparing of sacroiliac joint, which is a classic feature of ochronotic arthropathy. This case highlights the utility of bone scintigraphy in the evaluation of joint involvement as well as its correlation with clinical course and potential usefulness in the follow-up of this disease.
Research on alkaptonuria (AKU; OMIM # 230500) in Slovakia started in 1968 by the Research Laboratory (later on the Institute) for Clinical Genetics at Martin. Its first stage was focused on clinical, biochemical, genetic and epidemiologic questions and on the reasons for the high prevalence of AKU in Slovakia. Based on a screening programme of now over 611,000 inhabitants (509,000 newborns) the world-wide highest incidence of AKU (1 in 19,000) was recorded, and a total of 208 patients (110 children) were registered. Extensive genealogical studies (sometimes over two centuries) resulted in the fusion of several "unrelated" nuclear families into larger pedigrees and enabled tracing most AKU ancestors to their original geographic localities, predominantly in remote mountain areas. A likely founder effect was detected among the shepherd population of the so-called Valachian colonization that resulted in a high degree of inbreeding and persisting genetic isolation. These epidemiologic data formed the basis for molecular studies in collaboration with the Würzburg group. The AKU locus was mapped to human chromosome 3q2 by orthology to the mouse locus aku. Following the cloning of the homogentisate-1,2 dioxygenase (HGD) genes from human and mouse, nine different mutations were identified in 21 AKU index patients. These include 4 missense, 2 splice-site, 2 single-base insertion and 1 deletion mutation. The most frequent mutations among the 42 AKU chromosomes of the index cases are c.648G > A (Gly161Arg; 42.9%), and c.1278insC (Pro370fs; 19.1%). To date, the genotypes of 29 patients and of 74 gene carriers from 21 families have been established. The highest prevalence and allelic heterogeneity were observed in the Kysuce district with five different mutations. Molecular epidemiology studies by haplotyping were carried out to uncover the original geographic localities of all AKU index chromosomes. This strongly suggests that several founders have contributed to the HGD gene mutation pool. While there is no straightforward explanation for the clustering of independent mutations, the genetic isolation in the past is likely to be responsible for the high prevalence of AKU in Slovakia.
Alkaptonuria (AKU) is a rare metabolic disorder of phenylalanine catabolism that is inherited as an autosomal recessive trait. AKU is caused by loss-of-function mutations in the homogentisate 1,2-dioxygenase (HGO) gene. The deficiency of homogentisate 1,2-dioxygenase activity causes homogentisic aciduria, ochronosis and arthritis. We present the first molecular study of the HGO gene in Turkish AKU patients. Seven unrelated AKU families from different regions in Turkey were analysed. Patients in three families were homozygous for the R58fs mutation; another three families were homozygous for the R225H mutation; and one family was homozygous for the G270R mutation. Analysis of nine intragenic HGO polymorphisms showed that the R58fs, R225H and G270R Turkish AKU mutations are associated with specific HGO haplotypes. The comparison with previously reported haplotypes associated with these mutations from other populations revealed that the R225H is a recurrent mutation in Turkey, whereas G270R most likely has a Slovak origin. Most interestingly, these analyses showed that the Turkish R58fs mutation shares an HGO haplotype with the R58fs mutation found in Finland, Slovakia and India, suggesting that R58fs is an old AKU mutation that probably originated in central Asia and spread throughout Europe and Anatolia during human migrations.
Alkaptonuria (AKU) is an autosomal recessive disorder caused by the deficiency of homogentisate 1,2 dioxygenase (HGO) activity. The disease is characterized by homogentisic aciduria, ochronosis and ochronotic arthritis. AKU shows a very low prevalence (1:250 000), in most ethnic groups. Altogether 43 HGO mutations have been identified in approximately 100 patients. In Slovakia, however, the incidence of this disorder rises up to 1:19 000, and 10 different AKU mutations have been identified in this relatively small country. Here, we report detection methods developed for rapid identification of five HGO mutations. PCR primers were designed enabling detection of mutations IVS5 + 1G-->A, R58fs, and V300G by restriction digestion of amplification-created restriction sites (ACRS). Mutation G152fs is readily identified by heteroduplex analysis, and G161R by amplification refractory mutation system (ARMS) PCR.