Molecular diseases: mutations.

                                          MUTATIONS. 

In genetics, a mutation is a change of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element. Mutations result from unrepaired damage to DNA or to RNA genomes (typically caused by radiation or chemical mutagens), from errors in the process of replication, or from the insertion or deletion of segments of DNA by mobile genetic elements. Mutations may or may not produce discernable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes, including evolution, cancer, and the development of the immune system.

Insertions: occur when extra DNA is added into a existing gene.

Deletions: remove information from the gene. A deletion could be as small as a single base or as large as the gene itself.

Frame shift: mutations result from either addition or deletion of one ot two nucleotide bases. When this occurs the ''reading frame'' is changed so that all the codons read after the mutation are incorrect, even though the bases themselves may be still present.