When she was 5, Zina 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. The pediatrician said the combination of dry desert air in Las Vegas and the probability the child 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.

One night, when she was seven months pregnant with her second child, another nosebleed started, but 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.

Her second son, Antonio, was born in 2006. Three years later, daughter Elliyana Meade arrived prematurely by emergency caesarean section, and spent nearly two weeks in the neonatal intensive-care unit.

In May 2011, Martinez received a frantic call from the nurse at Daunte's elementary school. 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 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 stroke, coma, or death. A severe headache is often the first sign. Daunte 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, nearly miraculous given the severity of his bleed, doctors said.

They assured the worried mother that cerebral AVMs are very rare in children — she remembers being told there was a "one in a million chance" her other children might have one — and there was no need to test them.

Less than 18 months later, Elliyana, then 3, awoke in the middle of the night with a severe headache, then began vomiting violently and lost consciousness.

Her parents rushed her to the same hospital that had treated Daunte. 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 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 said. "I raised my hand and said, 'I have, for almost all of my life.' "

Solution

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

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by blood vessels that fail to develop properly. Ruptured AVMs are rare in people with HHT, but they 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 disorder 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 disorder is uncommon — it affects about one 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. Other symptoms include seizures, anemia and shortness of breath that is often misdiagnosed as asthma. Only about 10 percent of people with the disorder have cerebral AVMs, and many of those tangled vessels never rupture.

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.

"Most doctors have never heard of it and say to patients, 'Oh, you have nosebleeds.' Usually, it's kind of ignored," said McWilliams, an associate professor of radiology at UCLA.

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.

Scans revealed Elliyana had five AVMs in her brain; only one required immediate treatment. The others were monitored and treated later through surgery and embolization. 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, she contacted experts at UCLA and was referred to McWilliams, who has treated both Daunte and Elliyana.

Her middle child, Antonio, now 12,  has HHT, although he has not suffered any of the complications. 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, now 36, is uncertain which of her parents has HHT; neither has been tested.

She said she is devastated that all 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."

McWilliams said Martinez has no reason to feel guilty and has had a "particularly tough road." All her children have the disorder despite a 50-50 chance of inheriting the gene. The family's ordeal, he added, has been exacerbated by problems with their health-insurance coverage.

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