We put forward the hypothesis that sequence variations in the SPP1 promoter region might account for the higher SPP1 expression observed in PXE patients and therefore promote disease outcome.
DNA EXTRACTION AND MUTATIONAL ANALYSIS IN THE PROMOTER REGION OF THE SPP1 GENE
The entire regulatory region from -1864 to +317 of the SPP1 gene was initially amplified by PCR and then analyzed for sequence variations by partially denaturing HPLC (dHPLC).
We detected 9 sequence variations by performing dHPLC analysis of the SPP1 promoter sequence (Table 2).
Comparison of the allelic frequencies of the detected SPP1 promoter polymorphisms between PXE patients and healthy controls revealed the 4 variants c.
0; assuming a recessive model for PXE, the power of our study was 5% for these rare SPP1 promoter polymorphisms.
Significant LD was observed among the 6 SPP1 promoter polymorphisms, with a minor allele frequency of >5% as shown in Fig.
ASSOCIATION OF SPP1 PROMOTER POLYMORPHISMS WITH CLINICAL FEATURES
Allelic frequencies of the 3 SPP1 promoter variants were analyzed in subgroups of the PXE patient groups to evaluate an association with the clinical features shown in Table 1.
Altered expression of SPP1 has been found in the dermis of PXE patients analyzed by immunoelectron microscopy (19).