Zunika Crenshaw cringes as a tire swing whips her children around in circles just a little too fast. It's a sunny afternoon in the park, in Pleasanton, Calif. As her children play, she keeps a close watch on their breathing.

She says asthma is in her genes.

"You have a family, a person who has four kids, and all of them have it, including me," she says. "And then my mom has it, and my sister's two kids."

A little girl, 3-year-old Jhase, runs over to her, wheezing. Crenshaw grabs an inhaler, and her daughter breathes deeply from it.

"Perfect!" says Jhase. She lays her head against her mother's chest, then runs back to her brothers.

Crenshaw drops the inhaler in a pile of medications in her purse. She points to various pill bottles.

"Zyrtec, and this is ClariSpray. And there's albuterol and Dulera."

There are more drugs at home.

Asthma is the leading chronic disease among children, but it hits some populations harder than others.

According to the federal Centers for Disease Control and Prevention, black children are twice as likely to have asthma as white children. And black children are 10 times more likely than white kids to die of complications from asthma.

A team of scientists at the University of California, San Francisco, is on a mission to understand why. The researchers are digging into genetic clues that may have been overlooked until now.

Geneticist Marquitta White just published a study finding that the majority of genetic information scientists have on asthma patients doesn't apply to African-Americans.

"The majority of genetic studies, not just in asthma but in most diseases, are done in Caucasian- or European-descent populations," White explains. "The longest studies do not really include very many minority populations, which means that most patients aren't getting the best care, because we don't really know what the disease etiology is in their particular population."

Medications also work differently in different populations, according to Esteban Buchard, a pulmonologist at UCSF. As an example, he points to the small print on the instructions for a common asthma medication called Advair.

"It specifically says that if you're African-American and you take this, you have an eightfold risk of dying," he says.

The UCSF team is analyzing the genes of black, Mexican-American, and Puerto Rican children to better understand drug responses in each population.

"One of our hypotheses is that what's underlying this huge mortality in African-American children is the fact that the most commonly prescribed drug for asthma is albuterol," says White. "The problem is that not everyone responds to albuterol the same way. And actually, Puerto Rican and African-American children have the worst drug response. So you're looking at two populations with the worst drug response with the highest mortality. We have a feeling those things might be related."

The right drugs matter

Good treatment is key to preventing the kinds of serious asthma attacks that keep kids home sick.

The Crenshaw children are missing fewer school days since they started visiting the Breathmobile, a long motor home converted into an asthma clinic. The clinic is run by a nonprofit called the Prescott-Joseph Center. It travels throughout the East Bay offering free treatment to low-income families.

Inside, a medical assistant tests the lungs of a 5-year-old girl who's fiddling with her tight braids. The clinician pauses several times so the girl can blow her nose.

Pat Granberg, a pediatrician, asks the girl's mother about their living conditions, their neighborhood and their financial situation, to determine likely triggers for asthma. The disease can be caused by a number of factors, including obesity, air pollution, access to health care, molds, mildews, pets, perfumes and smoking. But Granberg begins an assessment by asking whether asthma runs in the family, because there's usually a genetic link.

One size doesn't fit all

"On average, 60 percent of what's going to determine whether or not you have asthma is going to be due to genetic factors," says White. She says depending on the population, that number could range from 35 to 90 percent.

"I think that what we should be striving for is equal care for everyone," says White, "and in order to do that you have to know what the disease is doing in everyone. That's step one."

Buchard believes a lot of health disparities could be explained if more minorities were included in genetic research. To illustrate his point, he looks back to when researchers studied heart disease only in men.

"Women present differently than men do for heart attacks," says Buchard. "So a whole generation of physicians were misclassifying and misdiagnosing women simply because women were not involved in the original clinical trials."

In 1993, Congress passed legislation requiring that publicly funded medical studies include more minorities. But a 2015 review of lung disease studies found only 5 percent of publicly funded research included patients of color.

This story originally appeared on KQED's blog Future of You.



Copyright 2020 KQED. To see more, visit KQED

DAVID GREENE, HOST:

Asthma - it is the leading chronic disease among children. And it hits some populations more than others. African-American children have asthma at much higher rates than white kids. Some of the causes are environmental. But as Lesley McClurg from station KQED in San Francisco reports, genetics plays a role as well.

LESLEY MCCLURG, BYLINE: Zunika Crenshaw cringes as a tire swing whips her kids around in circles on a sunny afternoon.

ZUNIKA CRENSHAW: You guys, be careful. I think that's a little too fast.

MCCLURG: The family is playing in a park in the city of Pleasanton, an eastern suburb of San Francisco. Four of her kids have asthma. So does Crenshaw herself. Three-year-old Jhase runs over to her mother wheezing.

CRENSHAW: Are you feeling OK?

MCCLURG: Crenshaw grabs an inhaler.

CRENSHAW: Ah, go ahead. Ready?

(SOUNDBITE OF INHALER)

CRENSHAW: OK.

JHASE: Perfect.

CRENSHAW: (Laughter).

MCCLURG: Crenshaw drops the inhaler in a purse full of medications.

CRENSHAW: Zyrtec. And this is ClariSpray. And there's albuterol and Dulera.

MCCLURG: And there are more drugs at home. When the kids start missing lots of school from asthma attacks, it's time to re-evaluate prescriptions and head to something called the Breathmobile, a long motorhome converted into a free-roaming clinic in the Bay Area.

MARY FRAZIER: Tiny breath in. Now take that big one, as big as you can. Deep breath.

MCCLURG: Inside the nonprofit's mobile clinic, a nurse tests the lungs of a 5-year-old girl fiddling with her tight braids. According to the Centers for Disease Control and Prevention, this African-American girl is twice as likely to have asthma compared to a white child and 10 times more likely than white kids to die of asthma-related complications.

Mary Frazier, a registered nurse with the Breathmobile, says asthma is caused by a number of external environmental factors, including air pollution, access to health care...

FRAZIER: ...Pests, molds, mildews, pets in the house, someone who smokes in the house.

MCCLURG: But asthma also runs in the family. And Frazier says her pediatric patients are more likely to have asthma if their parents suffer from the disease.

Marquitta White is a geneticist at University of California, San Francisco. She specializes in minority groups with asthma.

MARQUITTA WHITE: On average, 60 percent of what's going to determine whether or not you have asthma or not is going to be due to genetic factors.

MCCLURG: The subject hits home for White. She's African-American and has three nephews with the disease. White hopes her research can help fill in missing scientific data.

WHITE: The majority of genetic studies, not just in asthma but in most diseases, are done in Caucasian or European-descent populations.

MCCLURG: This general focus on Caucasians pushed Congress to pass legislation in 1993 requiring that publicly-funded medical studies include more minorities. But a recent review of studies since the law passed found that only 5 percent of publicly-funded research on lung disease included non-white patients.

WHITE: Which means that most patients aren't getting the best care because we don't really know what the disease ideology is in their particular population.

MCCLURG: In fact, White recently published a study finding that the majority of genetic information scientists have about asthma only applies to Caucasians.

White works in an ethnically-diverse lab, led by pulmonologist Esteban Burchard. He believes a lot of health disparities could be explained if more minorities were included in genetic research. Burchard uses the analogy of heart disease to make his point. There was a time when doctors only studied men who suffered from heart failure.

ESTEBAN BURCHARD: But women present differently than men do for heart attacks. And so a whole generation of physicians were misclassifying, misdiagnosing women, simply because women were not involved in the original clinical trials.

MCCLURG: And so Burchard's lab is now studying why inhalers provide relief for some children but not for others. The scientists are studying the genes of black, Mexican-American and Puerto Rican children to better understand drug responses in each population.

BURCHARD: This is the first thing that people throw away, the package insert.

MCCLURG: Burchard unfolds a giant sheet of directions inside a box of a common asthma medication.

BURCHARD: I've highlighted in yellow and circled in big red ink.

MCCLURG: He points to a technical paragraph printed in tiny font, stating that there's a much higher risk of death from the medication for African-Americans than for white patients. He says that's tragic.

He hopes there will be a day when researchers and doctors prioritize race and ethnicity when studying a disease or prescribing drugs. He says that would at least, in part, level the playing field and provide better care to African-Americans.

For NPR News, I'm Lesley McClurg in San Francisco. Transcript provided by NPR, Copyright NPR.