HEREDITARY HAEMORRHAGIC TELANGIECTASIA

Introduction

Hereditary haemorrhagic telangiectasia (HHT) also known as Osier-Weber-Rendu disease, was first described over 100 years ago. It is due to a faulty gene and is extremely variable, causing some people considerable distress, while others escape with much less severe problems. For the majority of patients, nosebleeds are the main problem, although bleeding from the lining of the stomach and intestines occurs in about 20% of cases.

The risk of passing HHT on to children

Everything about us, from eye colour to blood groups, is coded in units of inheritance known as genes. We each have about 50,000 pairs of genes, one of each pair from our mother and one from our father. Each time we make an egg or a sperm, there is a 50% chance of putting the other in - a bit like tossing a coin.

When a parent with HHT has a child, 50% of the time he/she passes on the faulty copy of the gene. If this happens, then the child will develop HHT. Each child of a person with HHT has a 50% risk of developing HHT. It does not depend on the sex of the child or whether or not previous children are affected. If you have four children in a row that develop HHT, then the risk to the fifth child is still 50%.

Symptoms of HHT

HHT does not usually cause any problems in early life. The first sign that a child has HHT is usually nosebleeds that are heavier and more frequent than those of other children. Over half of all patients with HHT have frequent nosebleeds by the age of 16, and over 90% by the age of 30 years. If you are over 30 and do not have nosebleeds or any little red spots (Telangiectases) on your hands or lips, then it is unlikely that you have HHT. In a recent study at Newcastle University, all the patients with HHT interviewed said that they had some symptoms before the age of 40.

Very occasionally, the faulty gene may be inherited and that person not show any signs of HHT. Usually however, if you do not have any signs of HHT by age 30, it means you have inherited the good copy of the gene and so do not have a faulty copy to pass on to your children.

Tests for HHT sufferers

If you have regular heavy bleeds from your nose or stomach and intestines, your doctor will monitor your blood to see if you are anaemic. This enables prompt treatment with iron tablets or a blood transfusion where necessary.

About 20% of patients with HHT have a problem with blood vessels in the lungs. This is called pulmonary arterio-venous malformation (PAVM) and can cause problems if it is not treated. We recommend that anyone with HHT is checked out for this problem. PAVMs can be detected by X-ray and by measurement of oxygen levels in the blood.

Other rare complications of HHT may need specific investigations. Your doctor will advise you if they are necessary in your case.

Available treatment

The best person to advise you about the treatment you require is your General Practitioner or hospital specialist. However, the following is a brief guide:

• Anaemia
  Any patient who has regular episodes of bleeding is at risk of becoming anaemic. Anaemia is a medical term used when there is insufficient iron in the blood. Iron can be replaced in 2 ways: either by taking iron tablets or by blood transfusion. Where possible your doctor will attempt to keep your blood iron levels up with iron tablets. Occasionally, if you have a very severe bleed then you may need a blood transfusion.
• Nosebleeds
  Various treatments have had some success in some patients but as yet there is no "magic cure".
  Cautery of troublesome vessels can produce temporary relief but long-term results are not so good. Most ENT surgeons tend to use cautery very sparingly, as repeated cauterisations may lead to damage to the surrounding nasal lining.
  Estrogens (hormone treatment) can be effective, particularly in women, but has troublesome side-effects in male patients which limits its usefulness.
  Laser treatment, like cautery, is aimed at a specific bleeding site. If you have several telangiectases in the nose or intestines then laser treatment is less effective, but the results of treatment in patients with small numbers of spots are quite encouraging. However, the treatment is still new and it will be some time before enough patients have been treated to form any firm conclusions. The equipment involved is very expensive and consequently the treatment is only available at specialised centres.
  Skin grafts are a "last resort" treatment when there is uncontrollable severe bleeding. The results are very variable.
• PAVM
  Until recently the only treatment for PAVMs was surgical removal and many patients and their doctors preferred to leave them alone if they were not causing any problems. However, it is now possible to pass a fine tube through a vessel in the top of the arm or leg into the lung, and block off the abnormal vessels with small teflon balloons introduced through the tube and inflated in the lung. Again, this treatment is available only at a few specialist centres such as the Hammersmith Hospital in London. Blocking off these vessels should reduce the risk of complications from PAVMS.
• Bleeding into the stomach and intestines.
  If you have problems with bleeding into the stomach and intestines, your doctor is likely to refer you to a gastro-enterologist for an endoscopy. This test involves looking at the upper portion of the gastro-intestinal tract with a fibre-optic tube (endoscope) the end of which is swallowed. If there are one or two particular bleeding sites these can be treated by laser, frequently to good effect. However, there are often several sites of bleeding and in this case, your doctor may choose to treat you "symptomatically", that is, with iron and blood transfusions.

Research into HHT

Because the underlying cause of HHT is still unknown, the only treatment that doctors can offer is directed at the symptoms of the disease. If the faulty gene involved could be identified and its role determined, then we would be nearer a specific treatment for HHT aimed at the underlying cause.

Research to find the faulty gene is underway in Newcastle Upon Tyne and also Ann Arbor in Michigan. All results obtained by the two groups will be shared in an attempt to get a quicker answer. Of course, it will be some time before scientific discoveries can be translated into practical treatment but it is an expanding field. There are other specialist groups researching into better ways of identifying and patients with PAVMS. Two major research centres are, in this country, the Hammersmith Hospital in London and, in the USA, at Yale University.

Summary

• The symptoms of HHT are variable; although HHT can be a major problem for some patients, others have infrequent nose bleeds or a few red spots
• It is important to look for treatable complications, such as PAVM, and all patients should have at least one chest X-ray and an estimate of arterial oxygen saturation