Neurological disorders comprise one of the largest groups of human diseases. Due to the myriad symptoms and the extreme degree of clinical variability characteristic of many neurological diseases, the differential diagnosis process is extremely challenging. Even though most neurogenetic diseases are individually rare, collectively, the subgroup of neurogenetic disorders is large, comprising more than 2,400 different disorders. Recently, increasing efforts have been undertaken to unravel the molecular basis of neurogenetic diseases and to correlate pathogenetic mechanisms with clinical signs and symptoms. In order to enable computer-based analyses, the systematic representation of the neurological phenotype is of major importance. We demonstrate how the Human Phenotype Ontology (HPO) can be incorporated into these efforts by providing a systematic semantic representation of phenotypic abnormalities encountered in human ge-
KEY WORDS: phenotype; ontology; neurogenetics; data integration; orphan diseases
Representation of Phenotypic Data in Clinical NeurologyThe differential diagnostic process for neurological disorders is one of the most challenging in medical practice, which is especially true for rare neurological diseases, defined as those that affect less than 1 in 2,000 persons. Unlike many other clinical disciplines, the day-to-day practice of neurology involves a pantheon of symptoms and long lists of differential diagnoses; the challenge is often to identify rare neurological diseases, especially those that require an individualized approach to clinical management [Chinnery, 2010]. Many rare neurological diseases are genetic in origin, and are associated with one or more functional and structural abnormalities of the nervous system. They originate from a wide spectrum of molecular and cellular defects and include skeletal muscle channelopathies, neuropathies, epilepsies, neurovascular disorders, neurocutaneous syndromes, mitochondrial diseases, nondegenerative movement disorders, inherited ataxias, neurodegenerative disorders, dementias, myopathies, and muscular atrophies. Currently, the classification of rare neurological diseases in the Orphanet database lists more than 2,400 different diseases. The differential diagnosis can be a daunting challenge for physicians, and affected patients may wait years before receiving a correct and precise diagnosis. For many patients, the underlying cause of the clinical manifestations may remain unknown.Several major international initiatives in neuroscience have emerged with the goal of developing computational models of the brain including the Neuroscience Information Framework and the Human Brain Project [Gardner et al., 2008]. Ontologies are playing a major role in these efforts to ensure interoperability across neuroscience databases, to integrate neuroscience information from disparate sources to improve our understanding of the brain, and to enable computer reasoning. In computer science, the word "ontology" is used to describe a structured, automated...