More rapid method for simultaneous measurement of tryptophan and kynurenine by HPLC.

hydroxyl-radical generation, leading to molecular and tissue damage. VE deficiency may affect nervous tissue in other ways, including overproduction of cytolytic phospholipids (22 ) and disturbance of brain monoamine metabolism (23 ). Other roles of VE, such as modulation of necrosis B and AP1 transcription factors and protein kinase C (24 ), are probably essential for its neuroprotective effect. Serum VE had rarely been investigated in unaffected family members of FA phenotype and was found to be within the reference interval in FA families (4 ) and decreased or within the reference interval in AVED families (4, 5, 25, 26). In our study, absolute and lipid-adjusted VE was lower in the parents of AVED patients, who are obligatory heterozygous. These lower concentrations are probably attributable to a mild decrease of hepatic -TTP activity in heterozygotes. In conclusion, AVED is relatively frequent in Tunisia and probably in North African countries. Measurement of serum VE would permit recognition of AVED patients, in whom VE supplementation may be beneficial. This could be particularly helpful in developing countries where genetic testing is not available and can be expensive. However, genetic testing is still the gold standard because VE could also be low in FA patients with malabsorption or nutritional problems. Serum VE, and especially lipidadjusted VE, may be useful for screening of heterozygotes in AVED families.