Further mapping of the properdin deficiency gene in a Tunisian Jewish family--evidence for genetic homogeneity.

The properdin deficiency gene has been localized to Xp21.1-Xcen; however, it is not clear whether the mutation responsible for the disease co-maps exactly with the structural properdin gene. Based on a recent study on a total of six families, the gene was found linked to DXS255 (theta = 0.00). As only a few families have been studied, it is not known whether the same gene is responsible for the disease in all families. In order to better localize the disease gene in Israel, we studied a Tunisian Jewish family with properdin deficiency for linkage with various X-markers. A maximum lod score of 1.93 at theta = 0.00 was calculated with the DXS7 probe while there was one recombination with DXS255. This study helps to better localize the properdin deficiency gene to Xp11.3-p21.1 proximal to DXS255 locus and confirms that there is no indication of genetic heterogeneity. Whether the properdin structural gene (PFC) and properdin deficiency locus are one and the same await demonstration of mutations in the structural gene in patients with properdin deficiency.