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  3. Search by sign

Simple search

Step 1 : Define the ruleStep 2 : Select the clinical signs or access the thesaurus

Step 3 : Search for matching diseases

This service is no longer maintained. A new service is currently under development and will soon be available. We apologise for any inconvenience caused.


This service enables you to retrieve information about diseases by searching clinical signs using a controlled vocabulary (Thesaurus) organised by main organs and systems.

Step 1: Select a query rule

  • Optional means that a disease is considered even if the sign is not listed in the disease profile. This is the default option.
  • Mandatory means that only diseases with this sign listed in the disease profile are considered.

Due to the large variability of most diseases expression, it is recommended that ‘optional’ be selected when there is no satisfactory search result with ‘mandatory’.

Step 2: Select signs

To start the search, enter at least one clinical sign.
You can enter clinical signs:

  • By entering a search term and clicking on the 'Search' button. The search will return a list of matching terms from which you may make a selection.
  • By using the thesaurus that groups first-level clinical signs from which you may select a subgroup of second-level clinical signs.
    The selected sign will then be entered into your list of search criteria. Up to five signs may be selected. The ‘search’ button will automatically be replaced by a ‘delete’ button which can be used to delete a sign if necessary. The options in step 2 will then appear on the screen.

Step 3: Search matching diseases

Once you have selected your search criteria (1 to 5) in the table, click on ‘Search’ in the Step 3 zone. A list of diseases corresponding to your search criteria will be displayed.
When criteria are optional, the diseases in the list are classified by decreasing order of number of matching signs.
To access information on a disease, click on it.


Not all rare diseases are currently indexed with their clinical signs as the indexing process is ongoing. This service is currently available for over 2,000 rare diseases only. As Orphanet does not include information on common diseases, this service cannot be used as a support to differential diagnosis with common diseases which should always be considered first. Establishing a diagnosis remains the full responsibility of the clinician using the Orphanet information service.

Orphanet aims to provide rare disease information to healthcare professionals, patients, and their relatives, in order to contribute improving the diagnosis, care and treatment of these diseases. Information in Orphanet is not intended to replace professional health care.

Orphanet cannot be held responsible for harmful, truncated or erroneous use of any information found in the Orphanet database.