phylogenetic relationships and identifying bacterial phyla in metagenomics studies. Sequences that are conserved within a clade but undergo some mutations, such as housekeeping genes, can be used to study species relationships. The internal transcribed spacer (ITS) region, which is required for spacing conserved rRNA genes but undergoes rapid evolution, is commonly used to classify fungi and strains of rapidly evolving bacteria. Medical research As highly conserved sequences often have important biological functions, they can be useful a starting point for identifying the cause of genetic diseases. Many congenital metabolic disorders and Lysosomal storage diseases are the result of changes to individual conserved genes, resulting in missing or faulty enzymes that are the underlying cause of the symptoms of the disease. Genetic diseases may be predicted by identifying sequences that are conserved between humans and lab organisms such as mice or fruit flies, and studying the effects of knock-outs of these genes. Genome-wide association studies can also be used to identify variation in conserved sequences associated with disease or health outcomes. In Alzehimer's disease there had been over two dozen novel potential susceptibility loci discovered Functional annotation Identifying conserved sequences can be used to discover and predict functional sequences such as genes. Conserved sequences with a known function, such as protein domains, can also be used to predict the function of a sequence. Databases of conserved protein domains such as Pfam and the Conserved Domain Database can be used to annotate functional domains in predicted protein coding genes. See also Evolutionary developmental biology NAPP (database) Segregating site Sequence alignment Sequence alignment software UCbase Ultra-conserved element References Computational phylogenetics Nucleic acids Protein structure Population genetics Molecular genetics Evolutionary developmental biology