Melanie and her son Louie, both of whom have HHT. Melanie Fennell

'You could have a ticking time bomb in your body': 9 in 10 people who have this serious genetic disorder don't realise

About 1,000 people in Ireland have HHT but many more are undiagnosed.

NINE IN 10 people who have Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu Syndrome, are unaware they have the condition.

HHT is a serious genetic disorder that causes abnormalities of blood vessels, leading to rupturing and bleeding. 

The most obvious symptoms of HHT, which can be life-threatening, are frequent unexplained nosebleeds and red spots on the skin. 

About 1,000 people in Ireland have the condition but many more are undiagnosed.

Melanie Fennell, from Whitechurch in Co Cork, first heard about HHT in 2000 when her brother Jason O’Sullivan had a stroke at the age of just 28. He appeared to be perfectly healthy so this came as a huge shock to the family.

“Following that, about a week to 10 days later, he haemorrhaged heavily from his lungs,” Melanie told

Doctors were unsure of what caused the stroke. “They thought he had meningitis, loads of different things came up,” Melanie said.

She said her mother started doing research and, based off Jason’s symptoms, asked the doctor if her son could have HHT. Her hunch was correct.

“It was pretty much unheard of at that time. There was no mention of HHT in the hospital, my mother brought it up after doing research,” Melanie recalled. 

Jason is now doing much better.

People with HHT have some blood vessels that have not developed properly and sometimes cause bleeding, known as arteriovenous malformations (AVMs).

Frequent bleeding can lead to anaemia and sometimes more serious problems that can affect people’s lungs, liver and brain.

Several members of the family 

Three of Melanie’s brothers have been diagnosed with HHT, as has her father and her six-year-old son Louie. She was diagnosed herself in 2003.

“We all suffered with nosebleeds growing up,” Melanie recalled, but it seemed like nothing to worry about at the time.

“My father also had very bad nosebleeds, and my uncles had problems with their lungs. Their father used to have nose bleeds too,” she added.

Many members of the older generation of the family were not diagnosed with HHT but Melanie said it seems obvious they also had the condition, stating: “We put two and two together.”

IMG_6875 Melanie with her sons Louie and Rio. Melanie Fennell Melanie Fennell

Several other members of the family have been diagnosed with the condition. Jason’s son Luke suffered from a brain haemorrhage when he was just two and a half weeks old, but is now about to turn four and “doing much better”.

Melanie’s niece, the daughter of a different brother, will have to undergo embolisation – a procedure that blocks the blood supply to the AVM.

Her eldest son Louie was diagnosed with HHT last year but he will have to wait until he’s 11 for scans to “figure out if he had lung issues or other issues” related to the condition and if he needs any intervention.

“Before we ever went for the test, we had called it, Louie would have nosebleeds and little red spots on his skin,” Melanie explained.

Her youngest son, two-year-old Rio, doesn’t have the condition.

Heavy nosebleeds

Melanie has regular nosebleeds but is “very unaffected by it compared to other people”.

I’d be anaemic a lot from the nosebleeds, it’s hard to keep my iron at a healthy level. This got worse when I was pregnant.

“The nosebleeds can be quite heavy and you’d almost feel faint from them. I also have abnormal vessels in my lungs, I had to have a C-section because of that,” Melanie said.

The blood vessels in her lungs are affected by HHT, but not to a huge degree, so she doesn’t need intervention bar iodine tablets and undergoing CT scans every five years as a “precaution” to see if things have progressed.

Despite not being overly affected by the condition in her day-to-day life, Melanie runs a beauty salon and often has to leave a client if her nose starts to bleed.

“You have to leave a client if you get a bleed, sometimes they can be hard to stop. You live with it, you get used to it. I plug my nose without even realising it, but it can be a nuisance,” she said.

“Thankfully the nosebleeds have lessened as I have gotten older. They did become more frequent and heavy during pregnancy, but subsided again afterwards.”

Melanie is sharing her story to raise awareness about HHT and mark Rare Disease Day, which is happening today.

As the vast majority of people who have HHT are undiagnosed, Melanie is encouraging people who have symptoms to discuss the condition with their GP and go for screening if needed.

“Nosebleeds can be a sign of nothing but they could also mean something; look at your family history.

“Potentially you could have a ticking time bomb in your body, go get your screening done.”


More information about HHT can be read on HHT Ireland’s website. The organisation supports people who have the condition, and was set up in the memory of the late Grace Nolan and Paul Woods who died suddenly, aged nine and 22 respectively, from HHT in their lungs.

The National HHT Centre opened in January 2003 at Mercy University Hospital in Cork. The centre’s mission is to identify individuals and families with HHT and give them the guidance and treatment they need.

More information about rare diseases can be read here.

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