Repeat sequence

Repeat sequences are usually DNA sequence that occur more than once in a genome. These can be caused by low-complexity sequence (stretches of repeating simple nucleotide sequences such as 'AAAAAAAAAAA' or 'GAGAGAGAGAGAGA'), genes found throughout a genome (e.g. F-boxes, ribosomal rRNA genes), transposable elements or other types of mobilized DNA, and other non-protein coding sequences. Repeat sequences are often discusses as:

• direct repeats, where the repeat sequences are in the same orientation in the genome (both 5'->3')
• inverted repeats, where the repeat sequences are in the opposite orientation in the genome (one 5'->3', the other 3'->5')