An elderly gentleman with chronic lower back and bilateral knee pain was found to have clinical and radiographic findings consistent with alkaptonuria. Diagnosis was confirmed by the detection of elevated homogentisic acid level in the urine using gas chromatography-mass spectrometry.
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.
Inborn errors of metabolism (IEM) are a group of disorders that causes abnormal function of biochemical pathways. Archibald Garrod des-cribed the first inborn error of metabolism in 1893. He described alkaptonuria in a patient whose urine turned black on standing and the development of arthritis in adult life.' Subse-quently, Garrod encapsulated the idea of IEM in 1908 with the concept of 'chemical indivi-duality'. Beadle and Tatum proposed the concept of one gene - one enzyme in 1945.2 Phenyl-ketonuria (PKU) was described in 1934 and amongst the first to be recognised as a cause of mental handicap with a biochemical basis.' Effective treatment for PKU with low pheny-lalanine diet was introduced in 1955. Molecular characterisation of genetic defects localised to alleles in various chromosomes were performed in the last two decades