Possible role of polyamines in gyrate atrophy

Gyrate atrophy (GA) is marked by hyperornithinemia and lowered ornithine amino transferase (OAT). However there are patients of GA without hyperornithinemia and those with hyperornithinemia without GA. Some cases of GA have been reported to have low lysine. The purpose of the study was to determine if polyamines, the metabolites of ornithine, and lysine have any diagnostic role in GA.

Ornithine in plasma was estimated by two-dimensional paper chromatography, with elution of the coloured spot, and the absorbance measured using a spectrophotometer at 560 nm. OAT assay in lymphocytes was done spectrophotometrically using ornithine as substrate. Blood and urinary polyamines were extracted with n-butanol, benzoylated and analysed with HPLC; putrescine, spermine, spermidine, and cadaverine were assayed individually at 254 nm with the UV detector using ODS, G18 column with 63% methanol as solvent.

Of the 7 patients investigated, 6 had features typical of GA. One was diagnosed to have atypical retinitis pigmentosa (case 3). The first five cases had elevated ornithine and diminished OAT, but cases 6 and 7 had near-normal ornithine and case 7 had near-normal OAT. However, all 7 patients had increased levels of total polyamines in urine compared to normals. Five had increased putrescine and three had increased spermine. All the 7 had decreased cadaverine in urine. Thus, though there were inconsistencies with ornithine and OAT, all the 7 patients had elevated polyamines from ornithine and decreased cadaverine.

In addition to estimating ornithine and OAT in GA, it is suggested that urinary polyamines may be analysed as the latter appears to correlate better with the clinical condition and help in the diagnosis to a greater extent. Moreover, while ornithine is an innocuous amino acid, polyamines are known to damage DNA and proteins.