A global alignment is one that compares the two sequences over their entire lengths, and is appropriate for comparing sequences that are expected to share similarity over the whole length. The alignment maximises regions of similarity and minimises gaps using the scoring matrices and gap parameters provided to the program. The EMBOSS program needle is an implementation of the Needleman-Wunsch [3] algorithm for global alignment; the computation is rigorous and needle can be time consuming to run if the sequences are long.