In vivo study of phytanic acid alpha-oxidation in classic Refsum's disease and chondrodysplasia punctata.
A series of in vivo experiments is described in which [1-13C]phytanic acid was given as an oral substrate to a healthy subject and two patients showing an impairment in phytanic acid degradation, one with Refsum's disease and one with chondrodysplasia punctata. After intake of the substrate by the control in a dose of 20 mg/kg body weight, the production of 13CO2 was measured in exhaled breath air and the concomitant formation of labeled 2-hydroxyphytanic acid and of pristanic acid was demonstrated by plasma analysis. After application of a substrate dose of 1 mg/kg body weight to the control, no substantial amounts of 13CO2 were measured, whereas time-dependent analysis of labeled 2-hydroxyphytanic acid in plasma yielded a concentration curve superimposed upon the baseline value (0.2 mumol/L) of the unlabeled substance. Phytanic acid accumulated in plasma from the Refsum's disease patient [649 mumol/L, controls > 1 y (n = 100): < 10 mumol/L], whereas the pristanic acid concentration was within the control range [1.4 mumol/L, controls > 1 y (n = 100): < 3 mumol/L]. Low amounts of 2-hydroxyphytanic acid were found normally present [0.04 mumol/L, controls > 1 y (n = 11): < 0.2 mumol/L], and formation of labeled 2-hydroxyphytanic acid could not be demonstrated after ingestion of [1-13C]phytanic acid in a dose of 1 mg/kg body weight. In addition to phytanic acid accumulation (232 mumol/L), the chondrodysplasia punctata patient showed an elevated 2-hydroxyphytanic acid plasma concentration (0.4 mumol/L), whereas the plasma pristanic acid level was in the control range (0.7 mumol/L).(ABSTRACT TRUNCATED AT 250 WORDS)
D000284:Administration, Oral; D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D002806:Chondrodysplasia Punctata / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D006801:Humans; D007223:Infant; D008297:Male; D010084:Oxidation-Reduction; D010831:Phytanic Acid / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D012035:Refsum Disease / Q000378:metabolism*
D005227:Fatty Acids; D002245:Carbon Dioxide; D010831:Phytanic Acid; C002844:pristanic acid