Trip Answers

Question answered:24/06/08

We searched the NLH Genetics and Screening Specialists Libraries but found no guidance on screening for Hereditary Haemorrhagic Teleangiectasy in patients with a relative with confirmed Osler-Weber-Rendu Syndrome.

 

However, the Hereditary Haemorrhagic Teleangiectasy (HHT) Foundation International considers the diagnosis and screening for the condition on their website:

 

“DIAGNOSIS
The clinical diagnosis of HHT is considered:
Definite when three or more of the criteria below are present
Possible or suspected when two of the criteria below are present
Unlikely when fewer than two of the criteria below are present
Diagnostic criteria for HHT:
Nosebleeds(epistaxis): spontaneous and recurrent
Telangiectases: multiple, at characteristic sites, including face, lips, oral cavity and fingers
Visceral AVM (pulmonary, cerebral, hepatic, spinal) or gastrointestinal telangiectases (with or without bleeding)
Family history: a first degree relative with HHT according to these criteria

 

Diagnostic laboratory-based genetic testing is available, but it is complex, expensive and has significant limitations compared to most clinically available genetic testing. Its recommended use is to diagnose younger at risk relatives - after the diagnosis of HHT has been confirmed according to the above criteria in one or more family members. Consultation with a medical geneticist or genetics counselor is usually helpful to determine whether a given individual or family is a candidate for genetic testing, understands that a negative result does not rule out HHT, and to coordinate testing within the family which begins with testing a clearly affected member.” [1]

 

An e-Medicine article on Osler-Weber-Rendu Syndrome states:

 

“Currently, no widely available laboratory studies exist to confirm the diagnosis of Osler-Weber-Rendu syndrome. In some large centers, a genetic test is available that tests for mutations in the endoglin gene found on chromosome 9 and the activin receptorlike kinase gene found on chromosome 12. However, some laboratory tests may be helpful in identifying some complications of Osler-Weber-Rendu (see section: http://www.emedicine.com/ped/topic1668.htm#section~workup).” [2]

 

A second e-Medicine article on Osler-Weber-Rendu syndrome notes:

 

“Prospective trials that determine ideal management of hemorrhagic telangiectasia (HHT) are limited by the small and varied population and by the multiorgan nature of the disease. A coordinated team approach is required.

 

Screening for pulmonary arteriovenous malformation (AVM) continues to generate controversy, with helical CT scan being advocated by some investigators and chest radiographs with pulse oximetry being advocated by others. Contrast echocardiography has also proven effective and has the advantage of identifying intracardiac shunts, whereas arterial blood gases or pulse oximetry shunt studies do not. Contrast echocardiography is noninvasive and has been shown to be highly sensitive. Some combination of the above studies would likely provide the best results.

 

Work in identification of specific gene mutations continues, and 4 distinct genetic loci are currently described. Early diagnosis of family members or confirmation with genetic testing of patients who fulfill Curaçao criteria may assist in the identification of those most at risk for specific sequelae. Participation in research and clinical trials, when available, will aid in discovery or clarification of the most appropriate interventions for this disease.” [3]

 

Finally, the PatientPlus website offers the following information on investigations and diagnosis in Osler-Weber-Rendu Syndrome:

 

“Investigations
Capillary microscopy, examining the capillary pattern of the fingernail, can be useful in screening for HHT, as most patients have detectable abnormalities before development of other signs.
CT, MRI scanning and possibly angiography are used to identify lesions.
Diagnosis
Diagnosis is made if at least 3 of the following are present:
• Epistaxes
• Telangiectasia
• Visceral lesions
• Appropriate family history.
Associated Diseases
• Osler-Weber-Rendu type 2 (HHT2) is a distinct but very similar disorder, mapped to chromosome 12. Hereditary haemorrhagic telangiectasia is associated with pulmonary arterial hypertension.
• Juvenile polyposis with hereditary haemorrhagic telangiectasia syndrome has been reported in a few families. There is inherited haemorrhagic telangiectasia associated with juvenile polyposis coli and colorectal cancer. The gene defect is on chromosome 18.

• A third type has also been described that is mapped to chromosome 5 and is called HHT3.” [4]

References
1. Hereditary Haemorrhagic Teleangiectasy Foundation International. (http://www.hht.org/medical-scientific/)
2. Silver N. Osler-Weber-Rendu syndrome. September 2006. (http://www.emedicine.com/ped/topic1668.htm)
3. Soriano P. Osler-Weber-Rendu syndrome. June 2006. (http://www.emedicine.com/med/topic2764.htm#section~FutureandControversies)
4. PatientPlus. Osler-Weber-Rendu Syndrome. September 2006. (http://www.patient.co.uk/showdoc/40001272).

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