The night the nosebleed started, Zina Martinez, seven months pregnant with her second child, was sitting in the living room of her Las Vegas home, eating a bowl of ice cream.

Martinez, 22, was used to nosebleeds. She’d had them nearly every day since she was 10, an annoying occurrence doctors repeatedly dismissed as insignificant — a probable result of the bone-dry desert air.

This one was different.

When Martinez pinched her nose closed to stop what was usually little more than a trickle, blood gushed out of her mouth. Her husband took her to a nearby emergency room where a doctor cauterized a vein inside her nostril, which stopped the bleeding.

When an ear, nose and throat doctor learned she had been taking aspirin every day for an unspecified clotting problem, he told her to stop: aspirin can trigger hemorrhaging. But he, like the otherdoctors Martinez saw over the years, did not investigate further.

Six years would elapse before Martinez learned what was really causing hernosebleeds — a finding that had life-changing implications for her family, which by then included three children.

"I had had signs and symptoms since I was 5 years old," said Martinez, now 36. "It was never really looked into."

When she was 5, Martinez suffered occasional seizures, but doctors couldn't identify an underlying cause. After two years on a potent anti-seizure medicine, doctors decided the drug was unnecessary.

Three years later, the nosebleeds started. Martinez said her mother was told by the pediatrician the combination of dry desert air and the probability she was picking her nose were most likely to blame.

In 2003, Martinez, then 20, gave birth to her son Daunte. Born five weeks premature, he was otherwise healthy. Her second son, Antonio, was born in 2006. In addition to the nasal hemorrhage, she developed preeclampsia — pregnancy-induced hypertension that can be fatal if not treated. Antonio was born healthy. Three years later, she again developed preeclampsia while pregnant with her daughter, Elliyana Meade. The baby, delivered by emergency Caesarean section, was premature and spent nearly two weeks in the neonatal intensive care unit.

In May 2011, Martinez was at home with Elliyana when she received a frantic call from the nurse at Daunte's elementary school. Martinez was told she needed to pick up her son immediately. The 7-year-old had complained of a severe headache, then began vomiting. The nurse worried he might have fallen on the playground and suffered a concussion.

Martinez raced to the school, then to a hospital. A CT scan revealed news much worse than a concussion. Daunte had suffered a massive brain bleed caused by an abnormal tangle of blood vessels in his brain known as an arteriovenous malformation or AVM. AVMs, which can occur in other parts of the body including the lungs, are typically present at birth and often cause no symptoms unless they rupture.

If a cerebral AVM ruptures, it can cause a stroke, coma or death. A severe headache is often the first sign. Martinez said she was told Daunte had a 50-50 chance of survival. He was placed in a medically-induced coma for several days, then underwent an embolization. The procedure involves threading a catheter through an artery in the groin and into the brain, then depositing glue or another substance to block the blood supply that feeds the AVM.

Daunte spent eight days in the hospital and suffered no brain damage, a circumstance Martinez said his doctors characterized as nearly miraculous given the severity of his bleed.

Martinez said she was terrified the same thing could happen to her other children and repeatedly peppered doctors with questions. Shouldn't they be checked? Could this be hereditary? She said doctors reassured her cerebral AVMs are veryrare in children — she remembers being told there was a "one in a million chance" her other children might have one — and no such screening was warranted.

Less than 18 months later, Elliyana, then 3, awoke in the middle of the night and said she was thirsty. After Martinez gave her some water, the little girl complained of a severe headache, then began vomiting violently and lost consciousness.

Her parents rushed her to the same hospital that had treated Daunte. Martinez remembers running into the ER cradling her daughter's limp body. A CT scan revealed the horrifying truth: An AVM in her brain had ruptured. By then, Elliyana, who had suffered two seizures, was in a coma.

Martinez said she was beside herself and remembers yelling at the doctors: "You told me last year I didn't need to get these kids checked! I want answers, and I want them now."

A few days later as Martinez and her husband were sitting by their daughter's bedside, a new doctor walked in.

"Which one of you has nosebleeds?" she remembers the hematologist asking.

"I remember thinking, 'Wow, how does he know?' " Martinez recalled. "I raised my hand and said, 'I have, for almost all of my life.' "

She said the blood specialist replied: "Well, you're the reason your kids' brains are bleeding. You have HHT."

"What's that?" Martinez remembers asking.

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by blood vessels that fail to develop properly; ruptured AVMs are among the most significant complications of the disorder.

In people with HHT, blood vessels may be formed without capillaries, tiny structures that connect arteries to veins. These vessels are unusually fragile and tend to bleed easily. Children with one parent who has HHT have a 50 percent chance of developing the disease themselves. Several genes are known to cause the disorder. Most can be detected through genetic testing.

HHT requires lifelong monitoring and treatment of complications that result. There is no cure. The disease is uncommon — it affects about 1 in 5,000 people worldwide — and varies in severity. The brain, lungs and gastrointestinal tract are typically affected, and it is estimated that 90 percent of those with HHT do not know they have it.

The most common symptom, which usually surfaces in childhood, is recurrent nosebleeds that range from minor to severe — sometimes so severe as to require transfusions. Other symptoms include seizures, anemia and shortness of breath that is often misdiagnosed as asthma.

Delayed diagnosis is the rule rather than the exception, said interventional radiologist Justin McWilliams, co-director of the HHT Center of Excellence at UCLA. On average, people with the disorder are diagnosed in their mid-30s.

"HHT is as almost as common as cystic fibrosis," a progressive genetic lung disease, said McWilliams, an associate professor of radiology at UCLA. "But unlike CF, most doctors have never heard of it and say to patients, 'Oh, you have nosebleeds.' Usually it's kind of ignored."

Diagnosing HHT is not necessarily complicated. Most of those affected have telltale, visible telangiectasia — tiny red spots that dot their hands and the inside of their nostrils or mouths. These spots, however, often do not develop until adulthood.

Their presence, combined with frequent nosebleeds, has enabled some doctors to make the diagnosis in the absence of a genetic test or before the advent of potentially catastrophic events, such as a brain bleed or a stroke.

Scans revealed Elliyana had five AVMs in her brain; only one required immediate treatment. The others were monitored and treated later through surgery andembolization. Although Elliyana lost her peripheral vision as a result of the brain bleed, she did not suffer other brain damage.

Following Elliyana's discharge, Martinez turned to the Internet and found Cure HHT, a Maryland-based national advocacy and support group. Through the auspices of the foundation, and based on recommendations by doctors in Las Vegas, she contacted experts at UCLA and was referred to McWilliams, who has treated both Daunte and Elliyana.

Her middle child, Antonio, now 12, has not suffered complications from HHT. He does not have AVMs and his health is being monitored.

A "bubble study" test, contrast echocardiography that uses sound waves to inspect blood vessels, revealed the presence of an AVM in Martinez's lung. An MRI scan of her brain showed evidence of a prior, small stroke. In 2013, she underwent treatment for the lung AVM performed by McWilliams at UCLA.

Martinez is uncertain which of her parents has HHT; neither has been tested. Her father, she said, has had years of medical problems the family blames on his exposure to the defoliant Agent Orange used during the Vietnam War.

She said she is devastated all of her children inherited the disorder and feels intensely guilty about passing HHT on to them.

"We all have severe anxiety and panic attacks" caused by the trauma of the children's emergency hospitalizations, Martinez said. The family is receiving therapy to help them cope. "I still blame myself for what my kids have gone through. If I'd known I had HHT, I'd never have had children."

Her faith and the support of her extended family and her doctors, especially McWilliams, have helped her persevere, she said.

McWilliams said Martinez has no reason to feel guilty and has had a "particularly tough road." All of her children have the disorder despite a 50-50 chance of inheriting the gene. And two have suffered serious brain bleeds, even though only about 10 percent of people with HHT have brain AVMs, and many never rupture. The family's ordeal, he added, has been exacerbated by problems with their health insurance coverage.

Although there are now more than two dozen centers around the country that specialize in treating HHT, a lack of recognition remains a formidable obstacle, McWilliams noted.

Early diagnosis is the best way to stave off serious consequences of the sort that befell Martinez's family.

“It’s important for doctors to think more deeply and recognize that sometimes a nosebleed is more than just a nosebleed,” he said.