Muhd,
1) First and foremost one must get past the idea that mutation means "bad, detrimental, suboptimal, etc". I think it would really be better to discuss
changes and whether or not those changes resulted, as a whole, in a species persisting to present day existence.
2) Many people that post in the same vein as you try to play a game whereby you decide what is a beneficial change and what is not. A case in point is that you have been informed of Sickle Cell Anemia. Now
you might make the initial judgement that this is/has been a detrimental change in DNA in a
Western European environment, BUT in fact this is a change that confers survivability in the environment that the organism lives in.
So, in answer to your challenge. Cut back on the "cheesy", B-rated, sci-fi movies (even though I like a few of these myself) Mutation=Change and that is it. EVERY SINGLE SPECIES you see surviving today is an example of a series of genetic/proteomic/environmental changes working in concert to assure that life continues on. It is naive of you to think that a single genetic mutation results in the difference between you and a dog....there is more than that between you and your sibling....unless maybe if you are a twin.