Combined factors V and VIII deficiency — the solution

Combined deficiency of coagulation factor V and factor VIII is an autosomal recessive disorder which has been observed in a number of populations around the world. However, this disease appears to be most common in the Mediterranean basin, particularly in Jews of Sephardic and Middle Eastern origin living in Israel. We have taken a positional cloning approach toward identifying the gene responsible for this disorder. We initially studied 14 affected individuals from nine unrelated Jewish families using a panel of polymorphic genetic markers spaced throughout the human genome. The combined factors V and VIII deficiency gene was mapped to a locus on the long arm of chromosome 18 with a maximal LOD score of 13.22. A detailed genetic analysis identified two distinct haplotypes among these families, suggesting two independent founders or, alternatively, a single ancient founder with a more recent split of these subpopulations. Further work to identify and characterize the gene responsible for combined factors V and VIII deficiency should provide important insights into the biosynthesis of these homologous proteins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73279/1/j.1365-2516.1998.440677.x.pd

Reply to: [Factor XI mutation and the origin of Ashkenazi Jews. Haematologica 2008; 93:e59]

Our current[1][1] and previous studies[2][2] unequivocally showed that the haplotype for factor XI type II mutation observed in Italians is identical with the founder haplotype discerned in Ashkenazi and Iraqi Jews as well as in Arabs.[3][3] An age estimate disclosed that this ancestral type I

Simultaneous genotyping of coagulation factor XI type II and type III mutations by multiplex real-time polymerase chain reaction to determine their prevalence in healthy and factor XI-deficient Italians

Background Factor XI deficiency is a rare autosomal recessive coagulopathy, which is, however, common among Ashkenazi Jews, in whom the so-called type II (E117X) and type III (F283L) mutations account for 98% of alleles. In non-Jewish populations, a higher level of allelic heterogeneity has been reported. However, the type II mutation was found in individuals from England, Portugal, and Italy, and haplotype analysis confirmed its Jewish origin. The aims of this study were to develop a rapid and accurate assay for the simultaneous detection of type II/type III mutations and to determine the frequency of these mutations in a large Italian population of healthy individuals and in a cohort of factor XI-deficient Italian patients. DESIGN AND METHODS: Type II and III mutations were detected using a newly developed multiplex four-color real-time polymerase chain reaction assay. Haplotype analysis was performed by either DNA sequencing or fragment-length analysis. RESULTS: Both type II and type III mutations were found among 3879 healthy Italians with an allele frequency of 0.00064 and 0.00051, respectively. Among the 31 analyzed factor XI-deficient patients, the type II mutation was found in three individuals in the homozygous state and in eight individuals in the heterozygous state (one compound heterozygote type II/III). Haplotype analysis revealed the Jewish origin of both mutations. Conclusions The newly developed assay is highly specific and reliable (0.02% false positives); and offers a useful means for the molecular diagnosis of factor XI deficiency. Type II and III mutations are present in the Italian population and should be searched for first in factor XI-deficient patients