CARRIER DETECTION BY MICROSATELLITE HAPLOTYPING IN 10 PROPERDIN TYPE 1-DEFICIENT FAMILIES

Properdin deficiency carrier identification is relevant, because prope rdin-deficient persons have an increased risk of contracting meningoco ccal disease. Vaccination against meningococcal disease at a young age may provide protection. Accurate detection of this deficiency is need ed. Microsatellite haplotyping with the PFC1 and PFC2 markers closely linked to the properdin gene locus at Xp11.3-Xp11.23 may offer an easy and accurate identification of carriers of the properdin deficiency g ene. The chance to study 91 relatives belonging to 10 families with co mplete (type 1) properdin deficiency offered a unique opportunity to a ssess whether properdin type 1 deficiency is associated with a distinc t microsatellite haplotype. Haplotyping with the closely linked PFC1 a nd 2 markers yielded five different haplotypes, which did not support the concept of a founder effect. Among the 28 women carriers, two had normal properdin levels and in five the PFC 1,2 polymorphism was not i nformative owing to homozygosity. Extending the microsatellite haploty ping with three additional markers (DXS1126, DXS426 and DXS7) yielded informative haplotypes in all meioses. We concluded that microsatellit e haplotyping using five markers in close proximity to the properdin g ene locus is an accurate method of detecting carriers of the properdin deficiency gene and of properdin-deficient persons within a family at a young age.