C. Long et al., DETECTION OF LATENT VARIEGATE PORPHYRIA BY FLUORESCENCE EMISSION-SPECTROSCOPY OF PLASMA, British journal of dermatology, 129(1), 1993, pp. 9-13
The plasma of patients with overt variegate porphyria contains porphyr
in with a fluorescence emission maximum at about 626 nm, which is diag
nostic for the condition. We have evaluated qualitative fluorescence e
mission scanning of saline-diluted plasma as a method for the identifi
cation of asymptomatic carriers of the gene for variegate porphyria. P
lasma from 3 6 unrelated patients with variegate porphyria, 136 of the
ir asymptomatic first- and second-degree relatives aged 15 years or ov
er, and 322 normal subjects was scanned. An emission maximum between 6
21 and 627 nm was observed in the 36 patients with variegate porphyria
and 54 of their relatives, but not in any normal subject, nor in 56 p
atients with other types of porphyria. For the detection of asymptomat
ic adult carriers of the gene for variegate porphyria, fluorescence em
ission scanning of plasma appears to be 100% specific, with a sensitiv
ity of 86% (95% confidence interval 71-98%). In contrast, the sensitiv
ity of faecal porphyrin analysis as a test for adult gene carriers was
36%. These results suggest that fluorescence emission scanning of pla
sma should replace faecal porphyrin analysis as the test of first choi
ce for this purpose.