Disclaimer

POSSUM Web may only be used by or under the supervision of a qualified and duly licensed medical practitioner or medical scientist who is a geneticist dysmorphologist or paediatrician and who is an expert in the diagnosis of birth defects. POSSUM Web functions as an electronic textbook about patterns of dysmorphism in humans and provides rapid access to information. POSSUM Web has been designed to provide additional assistance to practitioners in reaching diagnoses and for use as a teaching aid to provide appropriate training in birth defects. POSSUM Web does not make diagnoses. It produces a list of possible diagnoses for consideration by the experts.. POSSUM Web contains information on many but not all syndromes and the information may be incomplete and is subject to future change. POSSUM may be disturbing to people unacquainted with the subject of dysmorphism. The staff of The Murdoch Childrens Research Institute, who developed POSSUM Web, compiled the information and pictures in POSSUM Web, and the distributors of POSSUM Web and any corporation or institution which has installed POSSUM shall not be responsible for any decisions taken or inferences made by users of POSSUM Web. Copyright 2007. The Murdoch Childrens Research Institute POSSUM Web documentation and software may not be copied, photocopied, translated or transferred to any electronic medium or machine readable form in whole or in part without prior written consent of the Murdoch Childrens Research Institute This document may refer to hardware and software products by their trade name, and we acknowledge that, in most cases, these designations are claimed as trademarks by their respective companies. The information in this document is subject to change without notice.

Contact Details: We welcome any queries or suggestions that you might have. You can provide feedback via our web site: www.possum.net.au.

What is POSSUM and POSSUM Web?

POSSUM Web is a software tool that can help you to diagnose syndromes in your patients and to learn about syndromes in general. It is also a useful teaching tool. POSSUM Web contains information on more than 3000 syndromes, including chromosomal and skeletal syndromes. Our pictorial database includes:

• Pictures of cases
• X-ray, CT and MRI images
• Ultrasound images
• Diagrams
• Histopathology

By providing a flexible search facility, POSSUM Web saves you the time and effort usually involved in researching and cross-referencing syndrome information. You specify the traits exhibited by a patient and POSSUM Web provides a list of possible syndromes–including comments, citations, relevant pictures, and radiological images. Of course, the final diagnosis continues to rely on your skills in visually recognizing and comparing features. Our new product, POSSUM Web, delivers the syndrome information and frequent updates over the internet, while images will be distributed on DVD to subscribers, and will be installed on the computer’s hard disk.

Background and Development

The POSSUM team was led by Professors David Danks and Agnes Bankier at the Murdoch Institute and the Victorian Clinical Genetics Services Melbourne. This team has used computer-aided syndrome identification since 1980.

Over the years, POSSUM has been redeveloped in line with available technology platforms, and in 2006 developed as POSSUM Web - a web-based database which, for the first time, will also be accessible to the Macintosh community.

The POSSUM system, with its first videodisc, was launched in March 1987 and in 1988 won the Australian Information Technology Award in the category of “Systems Innovation of the Year”.

For nearly three decades many colleagues have assisted in establishing, writing and revising the POSSUM database, and the POSSUM Web team acknowledges the continued support and input from geneticists worldwide. POSSUM and POSSUM-web are also indebted to the computer support from our collaborating IT companies and personnel.

In August 2006 we were delighted and privileged to have Dr June Danks officially launch POSSUM Web at the International Congress of Human Genetics in Brisbane.

How We Maintain the POSSUM Web Database

In the POSSUM Web database, each syndrome is described by a set of traits including clinical, radiological and histological traits–this information is drawn from a cross-section of the literature. The database is updated continuously as new publications about a syndrome become available. To assess the traits that should be recorded for a syndrome we:

• Refer to the journals in which the syndrome was reported
• Check the pictures that have been provided by the author
• Review the Online Mendelian Inheritance in Man (OMIM) entry where relevant

To maximise the probability of retrieval in a search, most traits reported in the literature are included in a syndrome description–regardless of how frequently they occur. If there is more than one way of describing a feature such as ‘the forehead’ several clinical and radiological traits may be included.
A syndrome is an abstraction–individual patients do not manifest all the features of a syndrome. Sometimes the description of a syndrome in the literature is vague or incomplete. For example, the available literature on a syndrome may state that "cardiac abnormalities" occurred in that syndrome. Where specific information about a trait is not available, we use the group trait so that it is not overlooked during a search. For more information about group traits, refer to the section 'Working with Unknown or Ambiguous Traits' in Fine-Tuning the Search. For many syndromes, we also maintain information about patients who have been diagnosed with that syndrome. These patients were seen in our clinic and photographed. Patient descriptions only include traits present in that patient. We also maintain information about undiagnosed patients. If the traits exhibited by your patient match those of an undiagnosed patient, please contact us–we would be pleased to share more detailed clinical information about the patient, perhaps leading to the definition of a new syndrome.

Contributing to the POSSUM Imagebase

While many of our images are from the Royal Children's Hospital in Melbourne, we invite authors of publications and clinicians worldwide to contribute pictures to POSSUM Web. The easiest way to do this is to email electronic images (preferably jpeg format) to possum@mcri.edu.au. All contributors are explicitly acknowledged within the program.

Note: Material that has been previously published needs a release of copyright from the original publisher before it can be used in POSSUM Web. You need to let us know which of your illustrations have been published, and where, so that we can apply for release of copyright to use your pictures in POSSUM Web. Some journals insist that authors assign copyright on material and a subsequent release from the author is not necessary. Typically, copyright is jointly held, and releases from both the journal and the author are needed.

Installing and Setting-Up

This section provides information about installing the POSSUM Web software.

Software Requirements

To run POSSUM Web for Windows, you will need the following software:

• Microsoft Windows 2000 or XP Operating System
• Microsoft Internet Explorer 6 or 7
• Internet access — this may require payment of a separate fee to a service provider.

To run POSSUM Web for Mac OS X, you will need the following software:

• Mac OS X 10.4 (Tiger)
• Internet access — this may require payment of a separate fee to a service provider.

Hardware Requirements

To run POSSUM Web for Windows, you will need the following hardware:

• 1GHz CPU
• 512MB RAM
• Display with a resolution of at least 1024x768 and 16 bit color
• 1GB of available hard drive space
• DVD-ROM drive

To run POSSUM Web for Mac OS X, you will need the following hardware:

• 1GHz PowerPC CPU or any Intel Mac
• 512MB RAM
• Display with a resolution of at least 1024x768 and 16 bit color
• 710MB of available hard drive space
• DVD-ROM drive

Installing POSSUM Web

Installing POSSUM Web for Windows

Please Note:

• You must be logged in as a user with Administrative privileges in order to install POSSUM Web.
• Installation may take around 20 minutes, depending on the speed of your computer.
• The POSSUM Web installer will install the Microsoft .Net 2.0 runtime components, required for POSSUM Web

To Install POSSUM Web

1. Start Windows if it is not already running
2. Insert the POSSUM Web DVD into your DVD-ROM drive.
   • Choose the run option from the Windows start menu
   • Enter the letter of your DVD—ROM drive, followed by :\Windows\Setup.exe — e.g. D:\Windows\Setup.exe
   • Choose OK
3. If the Microsoft .Net 2.0 runtime is not already installed on your computer, the POSSUM Web installer will guide you through installing it.
4. The Welcome dialog box is displayed. Choose Next to continue.
5. Read through the License agreement, and choose the 'I Agree' button to continue.
6. The Choose Install Location dialog box is displayed. To change the directory for the POSSUM installation, choose the Browse button, select a new location, and choose Install to continue. Otherwise, choose Install to continue installing POSSUM Web to the default location.
7. When the installation is finished, you can launch POSSUM Web by choosing 'Programs — POSSUM Web — POSSUM Web' from the Start menu.

Installing POSSUM Web for Mac OS X

Note: POSSUM Web requires Mac OS X 10.4 — other releases of Mac OS X are not supported.

To Install POSSUM Web

1. Start Mac OS X if it is not already running
2. Insert the POSSUM Web DVD into your DVD-ROM drive.
   • Open the 'POSSUM Web' DVD icon that appears on your desktop
   • Open the 'Mac' folder
3. Drag the 'POSSUM Web' folder to the 'Drag POSSUM Web Here to Install' icon. This will install POSSUM Web to your 'Applications' folder.
4. You can launch POSSUM Web from the 'POSSUM Web' sub—folder of your 'Applications' folder.

Removing POSSUM Web

Removing POSSUM Web for Windows

1. Start Windows if it is not already running
2. Open the Control Panel (either by clicking the Start menu, and then 'Control Panel' —or— click the Start menu, then 'Settings', then 'Control Panel'). Then open 'Add or Remove Programs'
3. Click 'POSSUM Web' to select it, and click 'Change/Remove'
4. When asked 'Are you sure you want to completely remove POSSUM Web and all of its components', click 'Yes'
5. When removal is complete, you will be shown a message informing you that 'POSSUM Web was successfully removed from your computer'. Click 'OK'

Removing POSSUM Web for Mac OS X

1. Start Mac OS X if it is not already running
2. Open your 'Applications' folder in the Finder
3. Drag the 'POSSUM Web' folder to the Trash to remove the application

Quick Tour

Quick Tour provides an overview of the POSSUM Web workplace and helps you to become familiar with navigating around the system.

Starting POSSUM Web

Starting POSSUM Web for Windows

1. Start Windows if it is not already running
2. Open the Start menu
3. click 'Programs', click 'POSSUM Web', then click 'POSSUM Web' to start the application

Starting POSSUM Web for Mac OS X

1. Start Mac OS X if it is not already running
2. Open your 'Applications' folder in the Finder
3. Open the 'POSSUM Web' folder
4. Double-click the 'POSSUMWeb' item to start the application

Once the application is run, it will take a few seconds for the system to load, depending on the speed of your computer and your Internet connection.

The POSSUM Web application will start in 'Trait Search' mode. All other modes are accessible from the tabs on the POSSUM Web navigation bar.

POSSUM Web Basics

Most often, POSSUM Web is used to find syndromes based on the features or traits exhibited by a patient. The following table provides a high—level overview of this process using POSSUM Web:

Traits	Illustration
Start POSSUM Web. The application will automatically open in 'Trait Search' mode.
From the 'Traits' list, select the most significant traits exhibited by your patient. As you go, look-up trait definitions in the 'Trait Atlas' (see Finding out More about a Trait). Use search modes to refine your search (see Fine—Tuning the Search).
Run a syndrome search based on the traits you have selected.
Evaluate the candidate syndromes (see Evaluating Syndromes) in the POSSUM Web browser: Read the syndrome commentary and refer to the pictures that are available. Compare your patient's features with those listed for the syndrome. Check the clinic patients who have been diagnosed with the syndrome. Click on the link to the syndrome reference in the Online Mendelian Inheritance in Man (OMIM).
Preview images associated with a candidate syndrome.

Searching with POSSUM Web

POSSUM Web can take some of the time and effort out of researching and cross—referencing syndrome information in the literature. Using the flexible searching facility, you can find syndromes or patients that match the traits exhibited by your patient. If required, you can bypass traits and go directly to a syndrome to find out more about it.

Searching for Syndromes by Trait

POSSUM Web can help you to find syndromes with features that resemble those of your patient. By comparing the description and pictures with your patient, you can get closer to a diagnosis. Note: POSSUM Web is not an expert system or diagnostic tool, it is an aid to focusing on and evaluating the most likely syndromes.
To search for syndromes that match a set of traits:

1. POSSUM Web opens to display the trait list.
2. Click on a category to display the traits associated with it. You can find a specific trait by entering the trait name in the text field above the Trait list–To find a specific trait, enter the name (or part of it) and choose Search eg Click on Nose and all the traits relating to this category are displayed.
3. Click on a trait to add it to the Search Criteria. An asterisk is displayed beside the trait group to indicate that it has been added. You can also see the trait displayed in the Search Criteria list.

Finding out More about a Trait

As you build your Search Criteria, you may want to learn more about a specific trait. In POSSUM Web, all traits are contained in a Trait Atlas. The Trait Atlas enables you to:

• Look at the images available for a trait.
• Read a trait description.
• Find out the trait population--how many syndromes and patients are linked to the trait.
• Statistics indicate whether the trait is common or rare.

To use the Trait Atlas, click on a trait name in the 'Traits' list and choose the Trait Atlas button.

Strategies for Selecting Traits

In general, your searches should be based on the most striking features of your patient, not on a total description. You need to make decisions about which are the most significant traits. When searching for syndromes, you will get the best results if you use a small number of traits that:

• Are the most obvious and visually striking,
• Do not occur frequently across a large number of syndromes.

Check the Trait Atlas as you go, using the pictures to make comparisons with your patient. Searching with POSSUM Web is fast and flexible, you can restructure and reorganize your Search Criteria until you are satisfied with the results.

• To remove a trait from your Search Criteria:

  • In the Search Table, click on the tick box of the trait you want to remove. This will inactivate the trait from the next search
  • Alternatively, identify the trait in the trait list, and click on it to remove it from the trait table completely

• To remove all traits from the Search Criteria, choose the Clear button above the Trait Search window.

• When you are satisfied with your selection of traits describing your patient, push search and the possible diagnosis will appear in the search table. You can open each syndrome entry and review the features of the condition and the images associated with it.

Fine-Tuning the Search

If your search result provides a very long list of possible diagnosis you can refine your search by changing the mode of the trait.

You can alter the mode through the drop-down window next to the trait.

For more information about refining a search, refer to ‘Strategies for Selecting Traits’ in the previous section.

Too Many Matching Syndromes?

If you run a search and find that there are too many matching syndromes:

1. Review the traits that are in your search criteria:
   • Is this the best and most concise description of your patient?
   • Have you used uncommon traits where possible? If you use traits that are common to many syndromes, you increase the number of matching syndromes. You can find out if a trait is common by checking its statistics in the Trait Atlas. If your patient exhibits a trait that is quite rare, try including only that trait.
   • Are your traits too general? Where possible try and choose specific traits rather than group traits. Group traits make your search more general because each trait in the group is included in the search. In the Trait Selector, group traits are represented by the symbol
2. If you have revised your trait selections and still you are finding too many matching syndromes, you can try adjusting the score threshold. The score threshold determines how many traits should match before a syndrome is considered a candidate. For example–if the threshold is 4, each matching syndrome must contain at least 4 of the traits. This helps you to zero-in on the most likely syndromes–the higher the score threshold, the more limited the search results. You should be careful about setting the score threshold too high, as you might exclude possible diagnoses. To adjust the score threshold, use the plus and minus buttons on the Trait Search window:
3. Another way of refining your search is to mark a single trait as mandatory. Making a trait mandatory indicates that you are not interested in a syndrome unless it contains this trait. You can change a trait to mandatory by clicking in the Mode column. Keep clicking in the Mode column to cycle through the available search modes.
4. If you have tried the options described above and are still left with an unmanageable set of search results, you can try using the Excluded search mode. For example, if you are dealing with a 10 year old patient, you may not be interested in any syndromes that include the trait “Stillbirth/neonatal death”. To indicate this, you add the trait to your search criteria and then mark it as excluded. You should use this option with caution, to avoid overlooking possible diagnoses–for example, the syndrome you are looking for may sometimes result in “Stillbirth/neonatal death”.

No Matching Syndromes?

If you run a search and do not get any matching syndromes:

1. Try decreasing the score threshold. The score threshold is automatically set to about half of the number of traits you have selected–if you have four traits, the threshold is set to two. If you are not getting any matching syndromes with the current score threshold, decrease it and run the search again.
2. Maybe some traits in your search criteria are too specific, try using group traits. To broaden the scope of your search, replace a specific trait with the trait’s group term. In the Trait Selector, group traits are represented by the symbol .
3. Choose the most significant and uncommon feature exhibited by your patient, search on that trait alone.

Working with Unknown or Ambiguous Traits

It is not always possible for you to supply the precise traits to describe a syndrome or a patient. For example, you may know that a patient exhibits abnormal skin patches but have no further information about the type of abnormality (seborrhea, striae, dimples, etc.). To cater for this situation, POSSUM Web provides ‘group traits’ within each trait category. If you are not sure about specific traits, you can use the group trait. Group traits usually begin with the word ‘abnormal’.

Group traits encompass all the traits in the group. For example, searching for ‘Abnormal Patchy Skin Changes’ will give you the same results as a searching for all the individual traits in the group. You should choose specific traits where you can. Using group traits makes your search less specific and increases your chances of obtaining results that do not resemble your patient.

Note: A group trait can only contribute a count of one to a search result’s score, even though it implicitly includes all the traits that belong to the group.

Can’t Find the Appropriate Trait?

If you can’t find a suitable trait in the Trait Selector, you should use the group trait that is the closest match. Although most trait categories include the trait ‘other’, this is intended for use by the developers of POSSUM Web rather than as a trait to include in your search criteria.

Syndromes that are Linked to a Group Trait

Sometimes a syndrome may be directly associated with a group trait. For example, the available literature on a syndrome may state that ‘cardiac abnormalities’ occurred in that syndrome. In the absence of further details, the syndrome will be directly associated with the trait ‘Abnormal cardiovascular structure/function’. This tends to occur with chromosomal syndromes when the specifics are not readily available, or where a variety of cardiac defects may occur in patients with the same syndrome. Associating a syndrome with a group trait means implicitly that the syndrome manifests one or more traits in the group, but the specific trait is unknown or ambiguous. If you search for a specific trait within the group, POSSUM Web also checks for cases coded with the group term, since such cases might manifest the trait you are seeking.

Evaluating Search Results

When you have refined your trait search and have a manageable list of candidate syndromes, you can begin to look more closely at the search results.

Working with the POSSUM Browser

When you have obtained a list of Search Results, you can use the POSSUM Browser to look more closely at each result.

1. Click a result to view it in the POSSUM Browser. For information on performing a search, refer to Searching with POSSUM Web.
2. The POSSUM Browser is displayed, containing information about the selected result.

Looking at Pictures

While you have a syndrome or patient description displayed in the POSSUM Browser, you can look at the pictures that are available. These might include:

• Photographs
• X-rays
• Diagrams

To look at pictures:

1. Choose the Show/Hide Pictures button from the POSSUM Browser toolbar. The Picture Selector is displayed at the bottom of the window. To hide the Picture Selector, click on the Show/Hide Pictures button again.
2. Click on the image of interest which will appear in an enlarged view in the window.
3. Each time you select a picture it is displayed in a separate window and you can open as many views as you wish and move between them to compare.

Evaluating Syndromes

POSSUM Web is not an expert system or a diagnostic tool. While it can help you to focus on the possible diagnoses, you must still draw on your experience and expertise when evaluating a syndrome. When examining a syndrome description it might be useful to:

• Compare your patient's traits with those listed in the syndrome description and those illustrated in the pictures. If your patient does not exhibit a trait that is listed for a syndrome you may want to go back and check your patient. For example, the syndrome may include radiological traits that you have not yet investigated.
• Check the clinic patients who have been diagnosed with the candidate syndrome. Looking at case studies may give you a better idea of the range of traits that are exhibited by patients with the syndrome–it is very rare for a patient to display all the traits that have been recorded for a syndrome.
• Research the articles that are listed in the syndrome description.
• Check the syndrome commentaries to see if the syndrome has been compared with or distinguished from other syndromes.

Looking at Syndrome Descriptions

A syndrome description includes the following information:

Linking to OMIM Over the Internet

When evaluating a syndrome in POSSUM Web, you can link (over the Internet) to its reference in the Online Mendelian Inheritance in Man (OMIM). You can establish this link from a syndrome description.

Refer to the OMIM information for the syndrome you are currently working with. You can also follow links and move around through the OMIM web site.

Looking at Clinic Patients

A patient description includes the following information:

Searching for a Specific Syndrome

You can use POSSUM Web as a 'text book' to learn about or teach on specific syndromes. Note: POSSUM syndromes are intended to optimise matching during trait searches. You should always consult the core literature for more detailed information, particularly where management decisions are being made. You can search for a syndrome by:

• Syndrome Name
• Author Name

Searching by Syndrome Name

To search for a syndrome by syndrome name:

1. Select Syndrome Search Tab.
2. Enter the name of the syndrome you want to find. You can also enter part of the name. POSSUM Web will also search for synonyms or common alternatives for a syndrome name.
3. Choose the Search button. The matching syndromes are displayed in the syndrome list.
4. Click a syndrome name to see its description displayed in the POSSUM Browser.

Searching by Author Name

To search for syndrome by the name of the author who published it:

1. Choose the Author Search button
2. Enter the Author's name or part of the name in the text box and press Search
3. Choose from the list of authors displayed.
4. Click on the required author name. The Syndromes published by the selected author are displayed. Click a syndrome name to see its description displayed in the POSSUM Browser.

Printing Syndrome or Patient Descriptions

You can print a hardcopy of a syndrome or patient description. To do this:

1. Access the syndrome or patient description in the POSSUM Browser.
2. Choose Print from the File menu.
3. Choose the required options on the Windows Print dialog box.