Hereditary hemorrhagic telangiectasia

Diagnosis and Testing

How do I get tested for hereditary hemorrhagic telangiectasia?

A doctor may suspect a diagnosis of hereditary hemorrhagic telangiectasia (HHT) because of the presence of certain symptoms. There are criteria that a doctor may use. The presence of 3 of the 4 criteria is considered diagnostic of HHT. The four criteria:

  • Recurrent, spontaneous nosebleeds
  • Multiple telangiectasia on the skin and mucous membranes -Normally, very tiny blood vessels called capillaries connect arteries and veins. In HHT, these capillaries don't form properly and there are arteries and veins are connected directly. These abnormal connections are fragile and may rupture and bleed. When small arteries and veins are involved these connections are called telangiectasia. Telangiectasia are commonly found on the lips, tongue, face, chest, fingers, or mucous membrane that lines the inside of the cheeks.
  • Involvement of internal organs - the presence of arteriovenous malformations (AVMs) in the lungs, liver or brain. AVMs are abnormal connections between larger arteries and veins.
  • A first degree relative with HHT - A first degree relative is a brother, sister, parent or child of a person.

Molecular genetic testing is used to confirm a diagnosis of HTT in a child or person suspected of having the disorder. These tests involve studying the ACVRL1, ENG, GDF2, and SMAD4 genes for changes that cause the disorder. This can include sequence analysis, where a part or sequence of DNA within a gene is examined, or gene-targeted deletion/duplication analysis, where missing or extra regions of DNA are looked for within a specific gene. Molecular genetic testing must be done at specialized laboratories.

References
  • Shovlin C. Clinical manifestations and diagnosis of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome). UpToDate, Inc. website Accessed February 22, 2017. http://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-hereditary-hemorrhagic-telangiectasia-osler-weber-rendu-syndrome
  • McDonald J, Pyeritz RE. Hereditary Hemorrhagic Telangiectasia. GeneReviews website. Accessed February 23, 2017. https://www.ncbi.nlm.nih.gov/books/NBK1351/
  • Sacco KM, Barkley TW Jr. Hereditary hemorrhagic telangiectasia: a primer for critical care nurses. Crit Care Nurse. 2016 Jun;36(3):36-48. https://www.ncbi.nlm.nih.gov/pubmed/27252100
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More Diagnosis and Testing Content

Is there newborn screening for Hereditary hemorrhagic telangiectasia?

What tests support a diagnosis of hereditary hemorrhagic telangiectasia?

Who else in my family should I test for hereditary hemorrhagic telangiectasia?

Can hereditary hemorrhagic telangiectasia be detected before birth?

Is there newborn screening for Hereditary hemorrhagic telangiectasia?

Hereditary hemorrhagic telangiectasia (HHT) is not one of the disorders that is screened for at birth. People with mild symptoms may go undiagnosed well into adulthood. If a baby appears to have health problems that could be caused by HHT, the easiest way to begin testing for the disorder is to discuss it with the pediatrician or primary doctor. Referral to a metabolic genetic specialist may be necessary. Testing information in your area can also be obtained through a genetic counselor, to find a genetic counselor visit the National Society of Genetic Counselors Find a Genetic Counselor website. Information on how to add a disorder to newborn screening programs can be found at Save Babies Through Screening Foundation.

References
  • Save Babies Through Screening Foundation website. http://savebabies.org/
What tests support a diagnosis of hereditary hemorrhagic telangiectasia?

Molecular genetic testing is used to confirm a diagnosis of hereditary hemorrhagic telangiectasia (HTT) in a child or person suspected of having the disorder. These tests involve studying the ACVRL1, ENG, GDF2, and SMAD4 genes for changes that cause the disorder. This can include sequence analysis, where a part or sequence of DNA within a gene is examined, or gene-targeted deletion/duplication analysis, where missing or extra regions of DNA are looked for within a specific gene. Molecular genetic testing must be done at specialized laboratories.

People with HHT may undergo screening to determine the extent of the disease. Screening, which can include regular and advanced x-rays techniques, may be done to determine if there are arteriovenous malformations in the lungs, liver or brain.

There is a specific test used to look for AVMs in the lungs called a contrast echocardiogram, or an agitated saline transthoracic contrast echocardiography (agitated saline echo or bubble study). The Cure HHT Foundation has prepared a document that discusses this test.

References
  • The Cure HHT Foundation website. http://curehht.org/wp-content/uploads/2007/10/Echo-Bubble-Testing-in-Layman.pdf
  • Shovlin C. Clinical manifestations and diagnosis of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome). UpToDate, Inc. website Accessed February 22, 2017. http://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-hereditary-hemorrhagic-telangiectasia-osler-weber-rendu-syndrome
  • McDonald J, Pyeritz RE. Hereditary Hemorrhagic Telangiectasia. GeneReviews website. Accessed February 23, 2017. https://www.ncbi.nlm.nih.gov/books/NBK1351/
Who else in my family should I test for hereditary hemorrhagic telangiectasia?

Family members of people with hereditary hemorrhagic telangiectasia (HHT) can be screened for the disorder. They would undergo a basic clinical examination, be screened for anemia and iron deficiency, and then be screened for a pulmonary arteriovenous malformation (AVM). They may or may not be screened for AVMs in other organs.

In a family with HHT, genetic testing can be done to see whether other family members have the disorder. However, the specific gene changes in that family needs to be known. If known, all siblings and other at-risk relatives can be tested. Molecular genetic testing, which are tests that look for changes to genes, can be performed. A newborn child in a family with a history of HHT syndrome should be tested through molecular genetic testing. A genetic counselor or a physician with experience in HHT can provide advice about how a confirmed diagnosis can affect other family members. If a family member does not have the mutation that is known to affect the family, then this eliminates the need for screening tests. Medical geneticists can be found through the American College of Medical Genetics and a genetic counselor can be found through the National Society of Genetic Counselors.

References
  • McDonald J, Pyeritz RE. Hereditary Hemorrhagic Telangiectasia. GeneReviews website. Accessed February 23, 2017. https://www.ncbi.nlm.nih.gov/books/NBK1351/
  • Olitsky SE. Hereditary hemorrhagic telangiectasia: diagnosis and management. Am Fam Physician. 2010;82(7):785-90. https://www.ncbi.nlm.nih.gov/pubmed/20879701
  • Shovlin C. Clinical manifestations and diagnosis of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome). UpToDate, Inc. website Accessed February 22, 2017. http://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-hereditary-hemorrhagic-telangiectasia-osler-weber-rendu-syndrome
Can hereditary hemorrhagic telangiectasia be detected before birth?

Some parents may choose to have their child tested for hereditary hemorrhagic telangiectasia (HHT) before they are born. This is known as prenatal diagnosis. If the gene change(s) that causes HHT are known in a family, then molecular genetic testing (which can detect these changes) can be used for prenatal diagnosis. A sample of tissue can be taken from the placenta to test for changes in one of the genes known to cause the disorder. This test is called chorionic villus sampling. Another test is called amniocentesis, which involves taking a sample of the amniotic fluid that surrounds and protects a developing fetus. Cells known as amniocytes are taken from the fluid and studied for changes in these genes.

There are risks to the unborn baby of doing these tests before birth. Prenatal diagnosis is not common for HHT because most patients can liver normal to near normal lives with treatment. In people with severe expressions of the disorder, prenatal diagnosis may be recommended. Talk to your doctor or a genetic counselor in your area to discuss the risks and benefits of prenatal diagnosis.

References
  • McDonald J, Pyeritz RE. Hereditary Hemorrhagic Telangiectasia. GeneReviews website. Accessed February 23, 2017. https://www.ncbi.nlm.nih.gov/books/NBK1351/
  • Govani FS, Shovlin CL. Hereditary haemorrhagic telangiectasia: a clinical and scientific review. Eur J Hum Genet. 2009 Jul;17(7):860-71.

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