Gene mutations:
DNA is composed of a double helix, each side of which is a long string of four types of nucleotides. Each nucleotide possesses identical sugar-phosphate groups that contribute to the DNA framework but differs in the base that links the two frameworks. DNA is the code for amino acids used to build protein. When it was recognised that the genetic information was contained in the sequence of bases in the DNA, it became possible to understand the chemical nature of gene mutations. A change in one base is called a point mutation, which can alter protein, have no effect at all, or prevent the protein from being produced. If the DNA of a particular gene is altered, the protein codes may be missing or abnormal. just one missing or effected protein can make a massive difference on the body. Albinism, for example is the result of a missing protein and is marked by an absence of pigment from the hair, skin and eyes. This may arise from mutation within the mother which can then be inherited by her sons or it could occur in the male zygote so that the child develops the disease.