Which of the following statements regarding mutation are correct?

(i) Mutation is a phenomenon which results in alteration of DNA sequences and consequently results in changes in the genotype and phenotypes of an organism.

(ii) Gene/Point mutation is responsible for Sickle-cell anaemia.

(iii) Chromosomal mutation is responsible for Down’s syndrome.

(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 base pairs of DNA, causes frame-shift mutations but not by insertion of base.