Table 2.

The number of potentially missing IS-A relations detected in the UMLS source terminologies in English, as well as the terminology size and the number of existing IS-A relations that can be identified for each terminology

	Terminology size		Existing IS-A relations identified		Potentially missing IS-A relations identified
Source terminology	Concepts	Direct IS-A relations	Direct + indirect	Direct
MEDCIN	348 808	353 304	30 001	23 692	16 779
UWDA	61 127	62 285	34 564	24 594	10 865
FMA	102 595	104 341	54 644	39 274	7230
SNOMEDCT_US	401 832	994 499	19 859	14 529	3833
NCI	151 966	159 479	688	539	334
GO	49 907	77 067	9640	6246	250
SNOMEDCT_VET	36 527	40 689	82	81	23
HPO	16 222	18 313	37	30	11
CPM	3079	3853	7	7	10
UMD	27 309	12 889	0	0	8
PDQ	18 874	4298	43	36	8
CPT	40 892	14 072	1	1	7
ATC	5485	4969	2	2	1

GO: Gene Ontology; NCI: National Cancer Institute; SNOMEDCT_US: SNOMED CT (U.S. version).