Which of the following statements regarding mutation are correct?

i) Mutation is phenomenon which results in alternation of DNA sequences and consequently results in changes in the genotype and phenotype of an organism.

ii) Gene/Point mutation is responsible for sickle-cell anaemia

iii) Down’s syndrome is caused by aneuploidy

iv) In addition to recombination, mutation is another phenomenon that leads to variation in DNA

v) Chromosomal aberrations are commonly observed in cancer cells

 vi) Deletions of bases of DNA, causes frame-shift mutations but not by insertion of base