Background: Recently linkage and association of the chromosomal region 16p12-11 with enhanced IgE responsiveness have been shown. The gene coding for CD43 (sialophorin) has been localized to this region. Sialophorin represents a major sialoglycoprotein on the surface of human lymphocytes, monocytes and granulocytes. It is supposed to play an important role in human mast cell, T- and B-cell regulation and activation and has been described in connection with immunodeficiency diseases such as the Wiskott-Aldrich syndrome. Therefore, it can be designated as a candidate gene for atopy.
Methods: Using SSCP analysis and direct genomic sequencing, polymorphisms in the CD43 gene have been looked for and their association with atopy has been tested in a population of 260 largely atopic children and young adults.
Results: Three common polymorphisms in the coding part of the CD43 gene were found. Two of them are leading to amino acid exchanges, one from argine to cysteine at amino acid position 337 of the mature gene product and one from leucine to phenylalanine at amino acid position 341. Subsequent association studies revealed no obvious influence of R337C or L341F on IgE regulation (p = 0.47 and 0.43), neither in a cognate nor in an uncognate fashion.
Conclusion: We conclude that CD43 polymorphisms are unlikely to account for the observed linkage effect at 16p12-11. Whether the polymorphisms R337C and L341F adjacent to phosphorylation sites in the intracellular region of the protein alter the normal functioning of CD43 remains to be elucidated.