Pin It

Cajunetics 

A study of the Acadian gene pool helped one family understand their son's deafness. Someday, it might lead to a cure for certain genetic disorders.

Even on this overcast, muggy January day, Cory and Darci Heck's home in rural Albany, La., an hour's drive northwest of New Orleans, resembles a paradise for most young boys, and it is for the Heck's sons, Blake and Cameron. The house in the middle of the property is a large one-story where each boy has his own room filled with toys.

Outside, a rambunctious dark brown-and-white border collie, Belle, patrols the grounds, insisting that anyone around spend some time throwing her an old tennis ball. The yard backs up to a wooded area where 6-year-old Blake and 5-year-old Cameron like to go exploring. The family recently had a pond dug and hopes to have it stocked with fish soon. As long as they're wearing helmets, the boys can sometimes motor around the Heck's 5 acres on their 90-cc four wheelers.

These are things that most boys can only daydream about. Blake Heck (pictured on the cover with his mother, Darci, and his brother, Cameron) is living that dream, but his childhood didn't begin that way. It started as a quiet nightmare.

"He failed the test. He can't hear."

A nurse stood by Darci Heck's hospital bed and matter-of-factly reported that Blake, one day old, hadn't responded to auditory cues. Darci, who had gone through more than 20 hours of labor delivering Blake, tried to get out of bed to confront the nurse, but all she could manage was tell the nurse to get out.

The test was repeated, with the same result. Blake was deaf. The Hecks were devastated.

At first, Darci searched for answers, but not so much because she needed an explanation. She wanted someone to blame. Darci thought she found that person in the form of the doctor who delivered Blake. He was old, and she believed he had waited too long to remove the baby from the womb. Blake was probably deprived of oxygen, and that caused him to lose his hearing. Darci's parents agreed with her.

"I knew that baby should have come out sooner," Darci's mother said.

There was a simple reason for this tragedy: the doctor erred. It was his fault.

Decisions had to be made. How would the Hecks raise Blake? Should he immediately begin learning sign language and become a member of the deaf community, which doesn't view deafness as a handicap and deems sign language an alternative way of communicating? Another option would be to pursue an auditory and verbal path where the child learns how to lip-read, is fitted with hearing aids and is taught how to speak.

The Hecks decided on auditory and verbal instruction. At the age of three weeks, Blake was wearing his first hearing aids, and not much later he was enrolled in the Chinchuba Institute in Marrero, which bases its curriculum on teaching deaf children speech and language skills. At Chinchuba, a therapist taught Blake how to express his emotions; she taught him how to cry.

Darci needed no such instructions -- she cried every day. Blake's hearing aids didn't work and likely never would. Blake was severely deaf, unable to hear even very loud noises. It would be a long and difficult road for Blake to speak. During the day, while Blake was napping in his crib and with Cory away at work, Darci sometimes felt she needed to disturb the silence of her house.

"I would be so angry that I would clang pots and pans," she recalls. "Blake would sleep right through it."

When Carl Heck Jr., Blake's paternal grandfather, learned of Blake's deafness, he thought of his cousin, Kevin Talbot. Heck remembered that Talbot had two daughters who were deaf because of a genetic disease: Usher Syndrome. Heck visited his cousin and learned that Talbot's daughters probably weren't the first in the Talbot family line to have Usher Syndrome. Although they weren't officially diagnosed with Usher, two males in the Talbot family, long deceased, were deaf. They were also blind.

Usher Syndrome is a rare disease in which children are born deaf and eventually become blind because of retinal deterioration, or retinitis pigmentosa. Usher Syndrome patients usually begin to lose their sight during adolescence, progressing from night blindness to loss of peripheral vision to complete blindness.

A link between Usher Syndrome and the Acadians of Louisiana was initially established more than 40 years ago. Usher Syndrome occurs more frequently in Acadians than it does in the rest of the United States' population or in the world. The Talbots (Heck's mother was born Verna Mae Talbot) were one of the original Acadian families in Louisiana.

As he continued to investigate the link between his Cajun ancestors and Usher Syndrome, Carl Heck learned about a symposium at Nicholls State University on genetic diseases and the Acadian population. He convinced his son, Cory, to attend with him.

The symposium was called "Genetics of the Acadian People" and was led by Dr. Bronya Keats, head of the Department of Genetics at Louisiana State University's Health Sciences Center in New Orleans. She also is director of the Molecular and Human Genetics Center of Excellence, which is part of the Center for Acadiana Genetics and Hereditary Health Care at LSU New Orleans. At the symposium, Keats and other experts discussed why Acadians have a higher probability of genetic diseases such as Tay-Sachs disease, Friedreich's ataxia and Usher Syndrome -- and how the Acadian population plays a significant role in genetic research.

According to Keats, the increased probability of those afflictions is the result of gene mutations as well as Cajuns' geographic and cultural isolation.

"It's a matter of a relatively small genetic pool growing into a fairly large number of people," Keats says.

In 1632, some 300 French settlers, most of them from the La Chausee area in the West-Central region of France, arrived in French-controlled Nova Scotia, then called Acadia. The family names of these original colonists are familiar today in south Louisiana: Doucet, Cormier, Richard and LeBlanc, among others. Since "Acadians" were living in the frontier and isolated from others, marriages were almost exclusively between the offspring of the first 300 pioneers. Keats says the population grew from 300 to about 18,000 by 1755. Keats believes that the mutation that causes Usher Syndrome likely occurred accidentally in the DNA of one of these ancestral Acadians.

In order for a baby to be born with Usher Syndrome, the parents of the child must at least be carriers of the recessive mutated gene that causes the disease. When these two recessive genes are matched together, the result is Usher Syndrome. The likelihood of an American couple both being carriers is rare, but that likelihood increases in a small gene pool such as that of the first Acadians.

That gene pool became even smaller after 1755. In that year, the British, who were given Acadia in 1710 as part of a peace settlement, expelled the Acadians from their land. This forced deportation became known as the Le Grand Derangement (The Great Disturbance), and for many years the Acadians wandered between Europe and North America, seeking a permanent home.

From 1765-1785, more than 3,000 of that Acadian population of 18,000 migrated to southern Louisiana. This reduced population -- settling mostly in the 22 parishes that became Louisiana's "Cajun Triangle," including Avoyelles, St. Martin, Lafayette, Vermilion, Cameron and Assumption parishes -- kept to themselves and maintained their unique culture, with very few marriages outside of their community.

The Talbots, Blake Heck's ancestors, moved to Assumption Parish shortly after 1765.

After the symposium at Nicholls State, Carl and Cory Heck concluded that Blake had to be tested for Usher Syndrome, and after repeatedly lobbying Darci, the family took 6-month-old Blake to Bronya Keats' office. A positive test result would mean that Blake would someday lose his sight, but it would also provide the couple with the answer to their questions as to why Blake was deaf. In addition, the test would let Darci, already pregnant with Cameron by this time, know what the chances were that she would have another child with Usher.

Keats began interviewing the couple and initially concluded Blake's condition was not Usher Syndrome.

"When I first started speaking to them, I asked them about ancestry," Keats recalls. "Cory said he was Acadian, but Darci said no, so I thought it might just be deafness. But there were cousins on the Acadian side that had it, so I felt we should check it on the off chance Darci carried the gene. Sure enough, when we sequenced Darci's genes, it turned out she was carrying a form of the mutated gene."

Keats then confirmed that Blake had Usher Syndrome. Later, they learned that Cameron, who does not have Usher, is nonetheless a carrier. Because two recessive genes can cause Usher, there is a 25 percent chance that a couple carrying recessive genes will have offspring with Usher.

When Darci realized that Blake's deafness was nobody's fault, her anger dissipated and the Hecks became determined that their son's chances for a normal life would be as good as any other child's.

The next step was cochlear implants -- tiny electronic devices that can partially restore hearing for the severely deaf. The implants bypass damaged cells and convert sounds into electrical signals that directly stimulate the hearing nerve. A surgeon implanted the tiny device under the skin behind Blake's ear. After the surgery, Blake wore a headpiece microphone to capture incoming sounds.

Having the surgery doesn't guarantee the patient will benefit from the implants. Pre- and post-surgery counseling is vital, so patients can learn to interpret the sounds coming from the devices. Age is a factor in the surgery's success. The younger the patient, the more likely he or she will become accustomed to the implants. Most children have this type of surgery after the age of 2. Because hearing aids didn't benefit their son at all, the Hecks fought to have the surgery performed on Blake when he was just 14 months old.

The implants immediately made a difference. His hearing isn't normal -- sounds are amplified and sometimes other noises (such as an air conditioner kicking on or the din of a classroom) can distract Blake -- but he does hear. Today, Blake's speech has progressed to the point that he only goes to speech therapy for a monthly checkup.

Early diagnosis and cochlear implants have made a huge difference in Blake's life. He attends a mainstream first-grade class and is performing above average.

Linda Hebert's parents thought she was mentally handicapped. She is sitting at a long folding table in a large hall, which serves both as a meeting place and a makeshift church, in the Deaf Action Center in Lafayette. Hebert is signing to her daughter, Lynn Leblanc, recalling the day she asked her parents if they could have a baby so that Hebert, an only child, could have a sibling.

"They said, 'No. One is enough.' They thought they might have another mentally retarded child."

Hebert, 64, still believes she is mentally slow, but she certainly doesn't appear that way. Considering that she wasn't taught how to communicate until she was 12 years old and then received little formal education, Hebert, who has Usher Syndrome, has accomplished a great deal. She has raised four daughters, worked much of her adult life and, perhaps most importantly, smiles and laughs during the interview. Despite her struggles, Linda Hebert seems happy most of the time.

The center is a wooden, prefab building that matches the other gray-sided buildings in the Village Du Lac, an apartment complex for the disabled that is owned and operated by the Catholic Diocese of Lafayette. The complex feels quiet and isolated, like so many generations of Cajuns. Rain drizzles on its narrow, winding, one-way streets as a short, older woman, leaving after her regular visit to the center, guides herself along the sidewalk with the constant tapping of her extended mobility cane.

Myra Mouton, the center's director, says that the Deaf Action Center serves about 400 to 500 people with Usher Syndrome, along with other deaf people spread across a seven-parish area. She says the majority of those with Usher who use the center are elderly. Joining Hebert on this day are about 10 others with the disease. Hebert likes to come to visit with old friends. Mouton, who has been with the center more than 30 years, says this kind of socializing developed slowly.

"When I first got involved with the deaf and the deaf/blind population, people weren't out there as much as they are today," Mouton says.

Hebert's parents didn't want little Linda to get out. After her birth in Abbeville, she moved with her parents, Gladston and Beulah Hebert -- both Acadian, to New Mexico, where her father, an Air Force pilot, was stationed. It was there that the Heberts realized their daughter couldn't hear. For a while, they sought treatment, which amounted to doctors painfully pressing on her ears in order to somehow manipulate them into functioning.

When the treatments proved fruitless, Linda was enrolled in a school for the deaf. It was less a school than a prison for 3-year-old Linda. She says she didn't learn anything, and she spent her days doing little besides occasionally being allowed to draw.

When she turned 8, her father was transferred to a base in England, where life became even harder for the deaf girl. Hebert could neither speak nor read, but for some reason she was enrolled in a speaking school. The only way she could communicate was by elementary hand gestures, which weren't welcomed by the school's staff.

"I was pointing and gesturing," Hebert says. "The teachers would slap my hands down."

It wasn't until her family moved back to Abbeville when she was 12 years old that Hebert finally learned sign language. She was placed in Baton Rouge's Louisiana School for the Deaf, where she learned how to sign and read. She also played sports and received some vocational training. Hebert graduated from the school in 1961 with what Leblanc describes as the equivalent of an eighth-grade education.

Within in a year, she was pregnant and married to a fellow student, Joseph Lemar Griffith, who is deaf but not because of Usher Syndrome. The marriage lasted 14 years, and the couple produced four daughters, none of whom are deaf. The family lived on the Hebert family land, where her daughters today raise their own families in houses or mobile homes.

Linda is the fourth generation to own the 20-acre plot that runs along the Vermilion River in Abbeville. The land is her legacy, inherited from a silent father. Gladston Hebert committed suicide before ever learning to speak to his daughter through sign language. As Hebert relates this part of her story, she grimaces with her hands moving rapidly and angrily.

Hebert wasn't diagnosed with Usher Syndrome until she was 41 years old. Realizing that she would lose her sight, Hebert learned how to sign tactilely. Even with her sight failing, Hebert continued to perform physically demanding jobs, including dishwashing, working in a canning factory, even farming.

Until recently, Hebert was peeling shrimp and cleaning pots and pans at a local bakery two days a week. She lost that job when the bakery bought a dishwashing machine. Even with 20 acres of land, she is poor. She receives a small monthly allowance from Social Security Disability, and her daughters and grandchildren help her out. She knows her land very well and visits her extended family daily by using her cane.

Still, Hebert gets agitated -- maybe that's why her family considers her so hardheaded -- and she becomes visibly frustrated when she's asked about her daily routine.

"I'm bored, bored," she admits.

Not a slow mind, just a restless one.

Dr. Keats feels that educational outreach is a critical component of Acadians beginning to comprehend their genetic heritage. The federally funded Center for Acadiana Genetics and Hereditary Health Care performs outreach services by conducting symposiums like the one at Nicholls State that Carl and Cory Heck attended. Keats stresses that the point of these outreach events isn't to scare people.

"It's not focused on disease, but that will come out," Keats explains. "Our biggest goal is to help them understand genetics."

In fact, understanding genetics and the role mathematical probability plays in it, should dispel some Acadians' fears of genetic disease. As Keats is quick to point out, even with a restricted gene pool, genetic disease within the Cajun population is still a rarity. About 1 in 70 Acadians carries the recessive gene that causes Usher. For the rest of the United States population, it is approximately 1 in 100. From there, the person has to couple with another carrier, again very unlikely. One in 20,000 Acadian children are born with Usher Syndrome compared with 1 in 50,000 nationally. Keats reminds people that Cajuns and similarly small populations like them aren't the only ones with defective genes.

"We all have these," Keats says. "We all have at least a dozen or more of these bad genes, but they're paired with normal genes, so there isn't a problem."

While a smaller gene pool has caused some genetic disease within the Cajun population, it also has allowed researchers to better understand certain genetic diseases -- and to locate the genes and mutations that can cause them.

Dr. H.W. Kloepfer first discovered Usher Syndrome in the Acadians in 1966. This was an exciting discovery because, as Keats says, it allowed scientists to narrow down the disease's cause. Records from the Catholic Church demonstrated that many Cajuns unknowingly intermarried, sometimes from several family lines, with couples often being third, fourth or fifth cousins.

Instead of trying to analyze blood samples from Usher patients from around the world, which Keats says "will lead you nowhere," local researchers could focus on Cajun Usher patients.

"Dealing with a population like the Acadians," Keats explains, "means you can be pretty confident going in that all of the affected individuals are going to have two copies of the same mutation on the same gene."

Blood samples from Cajun Usher patients were collected and kept at Coriell Institute for Medical Research, a repository for genetic disease samples. In turn, researchers from around the world could order copies of these samples for study.

By 2000, two studies pinpointed the gene that causes Usher Syndrome in Acadians. It's called USH1C. Interestingly, while Keats was one of the researchers involved in the discovery, her research paper focused on a Lebanese family, which had members with Usher that was caused by the same gene. A group of researchers in London, using the Acadian samples, were likewise able to identify the USH1C gene. Although it was the same defective gene, the Lebanese family had a different mutation of USH1C than the Acadian sample. Researchers to date have confirmed that eight different genes can cause Usher Syndrome -- but only one, USH1C, causes it in Acadians.

Since identifying the gene, Keats and other researchers have hypothesized how to treat Usher Syndrome. When the disease strikes, blindness occurs slowly through retinal degeneration. The defective gene doesn't produce harmonin, a protein that helps maintain the retina.

"Our goal," Keats states, "is to prevent or slow down the retinal degeneration in these kids."

Keats believes that cellular therapy offers the best hope for preventing or slowing down retinitis pigmentosa. If a cell with a good copy of the gene could be introduced into the patient's retina, it might stimulate harmonin production. If the therapy works, it could help any Usher sufferer whose condition is caused by USH1C -- not just Cajun Usher patients.

To test cellular therapy, researchers replicated the disease in lab animals. For the past three years, Keats and her small team of graduate assistants attempted to create mice with Usher Syndrome caused by the USH1C gene. Their first aim was to produce carrier mice, which in turn could produce offspring -- each with a 25 percent chance of having Usher Syndrome.

The team successfully produced carrier mice and then mated them. Keats worried that Usher could be "embryonic lethal" in the mice, meaning they wouldn't survive to birth. Fortunately, the first litter was born alive. Because all mice are born deaf and don't start hearing until later, Keats and her team couldn't begin testing the mice until they were 20 days old.

At 20 days, Keats tested the mice. If the mice circled around themselves, that was a sign of deafness -- as was the absence of "prior reflex," which happens when a hearing mouse reacts to a loud noise. Like Darci Heck banging on pots and pans around her sleeping child, Keats loudly clapped around her litter of mice. While Darci prayed that somehow Blake would wake up to the noise, Keats hoped the mice wouldn't react.

Several mice were circling and showed no reaction to noise. A tissue sample confirmed that the mice had two copies of the defective gene. That test was completed more than year ago. Since then, Keats has produced more mice with the defective genes in order to have a large enough sample size for her research. Currently, they are waiting to find out if these mice will become blind. If they do, then future offspring can be used to test out any cellular therapy. Keats is optimistic.

"Our data is looking good that the mice are losing their vision."

Blake Heck is like many 6-year-old boys. When you ask him what he likes to do in school, Blake doesn't mention reading or mathematics.

"I like playing with Play Dough, playing at recess and watching movies," Blake says.

Darci Heck just shrugs.

"He's normal," she says.

Blake's circumstances are far from normal, however. He was born deaf because of Usher Syndrome, and his parents once lived in Boutte so they could be closer to the Chinchuba Institute. They later moved to Albany, where they knew Blake would be mainstreamed in school. By far the biggest decision they made was giving Blake cochlear implants. In doing so, they chose a path that makes Blake an outcast to many of those in the deaf community.

Keats says the deaf community doesn't view itself as handicapped, and some in that community ostracize those who get implants. This past holiday season, Blake and his mom were shopping in the Mall of Louisiana in Baton Rouge when they spotted a group of deaf teenagers.

As Darci and Blake walked toward them, the teens began signing and making annoyed facial expressions.

"Three or four of them started signing, 'Why would they give him implants? Bad mother.'"

Like any good mother, Darci drew her child away. She explained to Blake that not everyone looks positively on his implants, but that's okay, because the implants have helped him so much. For now, they enable him to live a typical little boy's life.

Blake knows that someday he will begin to lose his sight. His mom says he occasionally becomes anxious about it, but, like his father, he is even keeled and, for a 6 year old, rarely displays too much emotion. Perhaps someday he'll realize how far he has already come -- how his life is connected to, but vastly different from, that of an old woman living along the Vermilion River -- and how his future, like that of all children, is filled with potential, including the potential for a cure.

click to enlarge TRACIE MORRIS-SCHAEFER
click to enlarge LSU genetics researcher Dr. Bronya Keats is using mice to - study cellular therapies for Usher Syndrome. She's pictured - here with graduate student Jennifer Lentz in Keats' genetics - lab. - TRACIE MORRIS SCHAEFER
  • Tracie Morris Schaefer
  • LSU genetics researcher Dr. Bronya Keats is using mice to study cellular therapies for Usher Syndrome. She's pictured here with graduate student Jennifer Lentz in Keats' genetics lab.
click to enlarge When Linda Hebert, was born 64 years ago, little was - understood about Usher Syndrome and her deafness was - misconstrued as mental retardation. She didn't learn to - communicate through sign language until she was 12. - Though she has successfully held jobs through her adult - life and has raised four daughters, she still considers - herself to be mentally "slow." The disease now is causing - her eyesight to fail. - TERRI FENSEL
  • Terri Fensel
  • When Linda Hebert, was born 64 years ago, little was understood about Usher Syndrome and her deafness was misconstrued as mental retardation. She didn't learn to communicate through sign language until she was 12. Though she has successfully held jobs through her adult life and has raised four daughters, she still considers herself to be mentally "slow." The disease now is causing her eyesight to fail.
Pin It

Tags: ,

Comments

Subscribe to this thread:

Add a comment

Submit an event Jump to date

Latest in News

© 2014 Gambit
Powered by Foundation