RESUMO
BACKGROUND: Recent evidence suggests that brain-derived neurotrophic factor (BDNF) is an attractive candidate for modifying age at onset (AO) in Huntington disease (HD). In particular, the functional Val66Met polymorphism appeared to exert a significant effect. Here we evaluate BDNF variability with respect to AO of HD using markers that represent the entire locus. METHODS: Five selected tagging polymorphisms were genotyped across a 65 kb region comprising the BDNF gene in a well established cohort of 250 unrelated German HD patients. RESULTS: Addition of BDNF genotype variations or one of the marker haplotypes to the effect of CAG repeat lengths did not affect the variance of the AO. CONCLUSION: We were unable to verify a recently reported association between the functional Val66Met polymorphism in the BDNF gene and AO in HD. From our findings, we conclude that neither sequence variations in nor near the gene contribute significantly to the variance of AO.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/genética , Doença de Huntington/genética , Polimorfismo de Nucleotídeo Único , Adulto , Fatores Etários , Idade de Início , Códon , Humanos , Metionina/genética , Pessoa de Meia-Idade , Repetições de Trinucleotídeos , Valina/genéticaRESUMO
Generation of mouse models by introducing transgenes using homologous recombination is critical for understanding fundamental biology and pathology of human diseases. Here we investigate whether artificial transcription activator-like effector nucleases (TALENs)-powerful tools that induce DNA double-strand breaks at specific genomic locations-can be combined with a targeting vector to induce homologous recombination for the introduction of a transgene in embryonic stem cells and fertilized murine oocytes. We describe the generation of a conditional mouse model using TALENs, which introduce double-strand breaks at the genomic locus of the special AT-rich sequence-binding protein-1 in combination with a large 14.4 kb targeting template vector. We report successful germline transmission of this allele and demonstrate its recombination in primary cells in the presence of Cre-recombinase. These results suggest that TALEN-assisted induction of DNA double-strand breaks can facilitate homologous recombination of complex targeting constructs directly in oocytes.