title: Identification of the first Alu-mediated large deletion involving the F5 gene in a compound heterozygous patient with severe factor V deficiency.
abstract: Factor 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.
authors: Dipartimento di Biologia e Genetica per Scienze Mediche, Università degli Studi di Milano, Milan, Italy.
authors: Ilaria
authors: I
authors: Guella
authors: Elvezia Maria
authors: EM
authors: Paraboschi
authors: Willem A
authors: WA
authors: van Schalkwyk
authors: Rosanna
authors: R
authors: Asselta
authors: Stefano
authors: S
authors: Duga