3 1 0 http://purl.obolibrary.org/obo/SO_0001059 sequence_alteration 'sequence_alteration' SubClassOf 'sequence_feature' 'sequence_alteration' SubClassOf 'sequence_comparison' http://purl.obolibrary.org/obo/SO_0001060 sequence_variant 'sequence_variant' SubClassOf 'sequence_comparison' http://purl.obolibrary.org/obo/SO_0002072 sequence_comparison 'sequence_comparison' SubClassOf 'sequence_feature' http://purl.obolibrary.org/obo/SO_0002119 allelic_frequency 'allelic_frequency' SubClassOf 'variant_frequency'