Article

Clinical Diagnostics in Human Genetics with Semantic Similarity Searches in Ontologies

Institute for Medical Genetics, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
The American Journal of Human Genetics (Impact Factor: 10.93). 10/2009; 85(4):457-64. DOI: 10.1016/j.ajhg.2009.09.003
Source: PubMed

ABSTRACT

The differential diagnostic process attempts to identify candidate diseases that best explain a set of clinical features. This process can be complicated by the fact that the features can have varying degrees of specificity, as well as by the presence of features unrelated to the disease itself. Depending on the experience of the physician and the availability of laboratory tests, clinical abnormalities may be described in greater or lesser detail. We have adapted semantic similarity metrics to measure phenotypic similarity between queries and hereditary diseases annotated with the use of the Human Phenotype Ontology (HPO) and have developed a statistical model to assign p values to the resulting similarity scores, which can be used to rank the candidate diseases. We show that our approach outperforms simpler term-matching approaches that do not take the semantic interrelationships between terms into account. The advantage of our approach was greater for queries containing phenotypic noise or imprecise clinical descriptions. The semantic network defined by the HPO can be used to refine the differential diagnosis by suggesting clinical features that, if present, best differentiate among the candidate diagnoses. Thus, semantic similarity searches in ontologies represent a useful way of harnessing the semantic structure of human phenotypic abnormalities to help with the differential diagnosis. We have implemented our methods in a freely available web application for the field of human Mendelian disorders.

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    • "Of particular importance for these annotation-based scores is the concept of information content—a logarithmic transformation of rareness of annotations at or below each term as determined by association of the knowledge catalogs (e.g., the set of OMIM diseases) to the ontology. To compute annotation-based similarities, we used a version of the Resnik method [37], as symmetrized by Köhler, et al. [20]. In what follows, let D = an annotated disease, Q = a queried phenotype term set, d{t} = set of diseases annotated with term t, A{t} = set of terms t and all their respective ancestors, C{t} = set of terms t and all their respective children, and ||x|| = quantity of elements in set x. Let N be the total number of disease in the catalog that are annotated to the ontology. "
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    • "Up till now there does not exist a valid, generalpurpose definition of similarity measure. There do exist several special-purpose definitions which have been employed with success in cluster analysis [31] [33], search [2] [3], classification [11] [30] [35], recognition [28] [36] and diagnostics [1] [34]. In this section, first we give a notion of integral of intuitionistic fuzzy sets and then propose a new form of intuitionistic fuzzy implication , inclusion and give a similarity measure. "
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    • "Pesquita et al. [2009] provides an excellent review of the most popular similarity measures and their performance on GO-related tasks. More recently, the HPO has enabled the use of semantic similarity measures to predict clinical diagnoses [Köhler et al., 2009; Bauer et al., 2012; Zemojtel et al., 2014], to find representative model organisms for gene prioritization [Smedley et al., 2013], and most recently, to identify similar patients [Gottlieb et al., 2015]. "
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