SummaryFactor V (FV) deficiency is a rare autosomal recessive haemorrhagic disorder associated with moderate to severe bleeding symptoms. Conventional mutational screening leads to a complete molecular genetic diagnosis only in about 80–90% of cases. Large gene rearrangements, which could explain at least part of the “missing alleles” have not been reported so far in FV-deficient patients. In this work, we investigated a family with hereditary FV deficiency, in which the proband is compound heterozygous for a 205-Kb deletion, involving the first seven exons of F5, and the entire selectin P, L, and E genes, and for a novel splicing mutation (IVS12+5G>A). The deletion breakpoints, determined by using a combination of semi-quantitative real-time PCR and long PCR assays, occurred within AluY repeat sequences, suggesting an Alu-mediated unequal homologous recombination as the mechanism responsible for the deletion. The in vitro characterisation of the IVS12+5G>A mutation demonstrated that this mutation causes the skipping of exon 12 and the activation of a cryptic splice site. Low levels of residual wild-type splicing were also detectable, in agreement with the notion that the complete absence of FV may be not compatible with life.
Molecular characterization of human hepatic lipase deficiency. In vitro expression of two naturally occurring mutations.
