Quantitation of fibrillin immunofluorescence in fibroblast cultures in the Marfan syndrome.

The Marfan syndrome (MFS) is a heritable connective tissue disorder manifested by defects in the skeletal, ocular, and cardiovascular systems. Diagnosis of MFS is based on clinical findings. At present there are no laboratory tests for specific determination of this disorder. Defects in fibrillin, an elastin-associated microfibrillar glycoprotein, are now known to cause the variable and pleiotropic manifestations of MFS. Immunofluorescence studies of skin sections and dermal fibroblast cultures were the first to show this association. Most unequivocal cases of the Marfan syndrome exhibited an apparent reduction in fibrillin immunofluorescence. The prospect of examining patients whose clinical findings suggest a possible diagnosis of the Marfan syndrome has stimulated us to attempt quantitation of immunofluorescence. In the study described here we used computer-enhanced image analysis to establish "normal" and "abnormal" (Marfan) parameters of fibrillin immunofluorescence in dermal fibroblast cultures. Quantitation of fluorescence from control individuals showed a median of 21%, while the median fibrillin fluorescence in MFS patients was 6% with a confidence interval of < or = 15%. These findings were statistically significant to p < 0.01. It is hoped that these analyses may become a useful adjunct in the clinical diagnosis of MFS.