BRCA1 5272-1G>A and BRCA2 5374delTATG are founder mutations of high relevance for genetic counselling in breast/ovarian cancer families of Spanish origin.

The distribution of BRCA1 and BRCA2 germ line mutations in breast/ovarian cancer families varies among different populations, which typically present a wide spectrum of unique mutations. Splicing mutation 5272-1G>A of BRCA1 and frameshift mutation 5374delTATG of BRCA2 are highly prevalent mutations in Castilla-León (Spain), accounting for 18.4% and 13.6% of BRCA1 and BRCA2 positive families, respectively. To test the presence of founder effects, 9 Spanish 5272-1G>A and 13 5374delTATG families were genotyped with polymorphic markers linked to BRCA1 or BRCA2. All the 5272-1G>A families shared a common haplotype in eight markers (1.1 Mb region) and the mutation age was estimated in 15 generations (approximately 380 years). A conserved haplotype associated to 5374delTATG was observed in four markers (0.82 Mb). The mutation occurred approximately 48 generations ago (approximately 1200 years). Each mutation likely arose from a common ancestor that could be traced to a small area of Castilla-León and expanded to other Spanish regions. They can have a significant impact on the clinical management of asymptomatic carriers as well as on the genetic screening strategy to be followed in populations with Spanish ancestries.

Synthetic peptides representing T-cell epitopes act as carriers in pneumococcal polysaccharide conjugate vaccines.

Improvement of antibody responses to polysaccharides through their linkage to proteins is thought to be mediated by protein-specific T helper (Th) cells. To investigate whether the carrier protein of a conjugate could be substituted by a Th epitope, Streptococcus pneumoniae type 17F polysaccharide (PS) was bromoacetylated and coupled to different peptides via their carboxy-terminal cysteines. Two peptides, one from the mycobacterial 65-kDa heat shock protein (hsp65) and the other from influenza virus hemagglutinin, are well-known Th epitopes. Two other peptides were selected from the pneumolysin sequence by Th epitope prediction methods; one of them was synthesized with cysteine either at the carboxy or the amino terminus. Three conjugates consistently elicited in mice anti-PS immunoglobulin M (IgM) and IgG responses that were not observed upon immunization with derivatized PS without peptide. The same conjugates induced no anti-PS antibody responses in athymic (nu/nu) mice, whereas clear responses were elicited in euthymic (nu/+) controls, demonstrating the thymus-dependent character of these conjugates. Only the three conjugates inducing anti-PS responses were capable of eliciting antipeptide antibodies. One of the immunogenic conjugates was studied in more detail. It induced significant protection and an anti-PS IgG response comprising all subclasses. On the basis of these results and proliferation studies with peptide and conjugate-primed cells, it is concluded that linkage of Th epitopes to PS in the right orientation enhances its immunogenicity in a thymus-dependent manner. Future possibilities for using peptides as carriers for inducing antibody responses to poorly immunogenic saccharide antigens are discussed.