Study of C4A mRNA in mononuclear blood cells from a patient with SLE and C4A homozygous deficiency without C4A gene deletion.

C4A null alleles (C4AQ0) have an increased frequency in SLE patients. Surprisingly some of them have no detectable gene deletion. In order to characterize the level of the defect in such patients, we used a RT-PCR/nested PCR technique and detected the presence of C4A mRNA in normal amounts. Since maturation abnormalities are almost always accompanied by a decrease in mRNA concentration, this result suggests that the defect may be located at the translational level.