Alcaptonúria (ocronose): relato de caso de irmãos / Alkaptonuria (ochronosis): a case report of siblings

A Alcaptonúria é uma doença autossômica recessiva rara caracterizada pelo acúmulo de ácido homogentísico. Denomina-se também ocronose e manifesta-se por pigmentação azulada de tecidos orgânicos e urina enegrecida, além de artropatia. A seguir, será relatado o caso de irmãos portadores de artropatia ocronótica e a conduta ortopédica (AU)

Alkaptonuria is a rare autosomal recessive disease characterized by the accumulation of homogentisic acid. It is also called ochronosis and is manifested by bluish pigmentation of organic tissues and blackened urine, besides arthropathy. Here the authors report the case of siblings with ochronotic arthropathy and the orthopedic management (AU)

Alkaptonuria: A very rare metabolic disorder.

Alkaptonuria (AKU) is a very rare autosomal recessive disorder of tyrosine metabolism in the liver due to deficiency of homogentisate 1,2 dioxygenase (HGD) activity, resulting in the accumulation of homogentisic acid (HGA). Circulating HGA pass into various tissues through-out the body, mainly in cartilage and connective tissues, where its oxidation products polymerize and deposit as a melanin-like pigment. Gram quantities of HGA are excreted in the urine. AKU is a progressive disease and the three main features, according the chronology of appearance, are: darkening of the urine at birth, then ochronosis (blue-dark pigmentation of the connective tissue) clinically visible at around 30 yrs in the ear and eye, and finally a severe ochronotic arthropathy at around 50 yrs with spine and large joints involvements. Cardiovascular and renal complications have been described in numerous case report studies. A treatment now is available in the form of a drug nitisinone, which decreases the production of HGA. The enzymatic defect in AKU is caused by the homozygous or compound heterozygous mutations within the HGD gene. This disease has a very low prevalence (1:100,000-250,000) in most of the ethnic groups, except Slovakia and Dominican Republic, where the incidence has shown increase up to 1:19,000. This review highlights classical and recent findings on this very rare disease.