The Brown family at the Grand Tetons (2019). Clockwise from left, Christine, Kevin, Keagan, Connor, and Kellen.
But Christine Brown knew none of this when the hospital called saying that standard newborn screening of her son Connor had come back positive for PKU. It was urgent that they visit a special metabolic clinic the next day, which was about a three-hour drive away.
“I was told not to go on the Internet,” Christine recalls, “So when somebody tells you not to go on the Internet, what do you do? Even back in 2005, right.” What she saw were the worst examples of retardation, which was a common outcome from PKU before newborn screening became routine. “We were just in complete shell shock, our whole world just kind of shattered and went into a tail spin.”
“I remember feeding him the night before our clinic visit and almost feeling like I was feeding him poison because I knew that breast milk must have protein in it,” she says.
“Some of my first memories are of asking, ‘Mommy, can I eat this? There were yes foods and no foods.'"
Over the next few days the dedicated staff of the metabolic clinic at the Waisman Center at the University of Wisconsin Madison began to walk she and husband Kevin back from that nightmare. They learned that a simple blood test to screen newborns had been developed in the early 1960s to detect PKU and that the condition could be managed with stringent food restrictions and vigilant monitoring of Phe levels.
Everything in Your Mouth Counts
PKU can be successfully managed with a severely restricted diet. That simple statement is factually true, but practically impossible to follow, as it requires slashing protein consumption by about 90 percent. To compensate for the missing protein, several times a day PKU patients take a medical formula – commonly referred to simply as formula – containing forms of proteins that are digestible to their bodies. Several manufacturers now add vitamins and minerals and offer a variety of formats and tastes to make it more consumer friendly, but that wasn't always the case.
“When I was a kid, it tasted horrible, was the consistency of house paint. I didn't think about it, I just drank it. I didn't like it but you get used to it after a while,” recalls Jeff Wolf, the twang of Appalachia still strong in his voice. Now age 50, he grew up in Ashland, Kentucky and was part of the first wave of persons with PKU who were identified at birth as newborn screening was rolled out across the US. He says the options of taste and consistency have improved tremendously over the years.
Some people with PKU are restricted to as little as 8 grams of protein a day from food. That's a handful of almonds or a single hard-boiled egg; a skimpy 4-ounce hamburger and slice of cheese adds up to half of their weekly protein ration. Anything above that daily allowance is more than the body can handle and toxic levels of Phe begin to accumulate in the brain.
“Some of my first memories are of asking, ‘Mommy, can I eat this? There were yes foods and no foods,’” recalls Les Clark. He has never eaten a hamburger, steak, or ribs, practically a sacrilege for someone raised in Stanton, a small town in northeastern Nebraska, a state where the number of cattle and hogs are several-fold those of people.
His grandmother learned how to make low protein bread, but it looked and tasted different. His mom struggled making birthday cakes. “I learned some bad words at a very young age” as mom struggled applying icing that would pull the cake apart or a slice would collapse into a heap of crumbs, Les recalls.
Les Clark with a birthday cake.
Courtesy Clark
Controlling the diet “is not so bad when you are a baby” because that's all you know, says Jerry Vockley, Director of the Center for Rare Disease Therapy at Children's Hospital of Pittsburgh. “But after a while, as you get older and you start tasting other things and you say, Well, gee, this stuff tastes way better than what you're giving me. What's the deal? It becomes harder to maintain the diet.”
First is the lure of forbidden foods as children venture into the community away from the watchful eyes of parents. The support system weakens further when they leave home for college or work. “Pizza was mighty tasty,” Wolf' says of his first slice.
Vockley estimates that about 90 percent of adults with PKU are off of treatment. Moving might mean finding a new metabolic clinic that treats PKU. A lapse in insurance coverage can be a factor. Finally there is plain fatigue from multiple daily dosing of barely tolerable formula, monitoring protein intake, and simply being different in terms of food restrictions. Most people want to fit in and not be defined by their medical condition.
Jeff Wolf was one of those who dropped out in his twenties and thirties. He stopped going to clinic, monitoring his Phe levels, and counting protein. But the earlier experience of living with PKU never completely left the back of his mind; he listened to his body whenever eating too much protein left him with the “fuzzy brain" of a protein hangover. About a decade ago he reconnected with a metabolic clinic, began taking formula and watching his protein intake. He still may go over his allotment for a single day but he tries to compensate on subsequent days so that his Phe levels come back into balance.
Jeff Wolf on a boat.
Courtesy Wolf
One of the trickiest parts of trying to manage phenylalanine intake is the artificial sweetener aspartame. The chemical is ubiquitous in diet and lite foods and drinks. Gum too, you don't even have to swallow to receive a toxic dose of Phe. Most PKUers say it is easier to simply avoid these products entirely rather than try to count their Phe content.
Treatments
Most rare diseases have no treatment. There are two drugs for PKU that provide some benefit to some portion of patients but those drugs often have their own burdens.
KUVAN® (sapropterin dihydrochloride) is a pill or powder that helps correct a protein folding error so that food proteins can be digested. It is approved for most types of PKU in adults and children one month and older, and often is used along with a protein-restricted diet.
“The problem is that it doesn't work for every [patient's genetic] mutation, and there are hundreds of mutations that have been identified with PKU. Two to three percent of patients will have a very dramatic response and if you're one of those small number of patients, it's great,” says Vockley. “If you have one of the other mutation, chances are pretty good you still are going to end up on a restricted diet.”
PALYNZIQ® (pegvaliase-pqpz) “has the potential to lower the Phe to normal levels, it's a real breakthrough in the field,” says Vockley. “But is a very hard drug to use. Most folks have to take either one or two 2ml injections a day of something that is basically a gel, and some individuals have to take three.”
Many PKUers have reactions at the site of the injection and some develop anaphylaxis, a severe potentially life-threatening allergic reaction that can happen within seconds and can occur at any time, even after long term use. Many patients using Palynziq carry an EpiPen, a self-injection devise containing a form of adrenaline that can reverse some of the symptoms of anaphylaxis.
Then there is the cost. With the Kuvan dosing for an adult, “you're talking between $100,000 and $200,000 a year. And Palynziq is three times that,” says Vockley. Insurance coverage through a private plan or a state program is essential. Some state programs provide generous coverage while others are skimpy. Most large insurance company plans cover the drugs, sometimes with significant copays, but companies that are self-insured are under no legal obligation to provide coverage.
Les Clark found that out the hard way when the company he worked for was sold. The new owner was self-insured and declined to continue covering his drugs. Almost immediately he was out of pocket an additional $1500 a month for formula, and that was with a substantial discount through the manufacturer's patient support program. He says, “If you don't have an insurance policy that will cover the formula, it's completely unaffordable.” He quickly began to look for a new job.
Hope
It's easy to see why PKUers are eager for advances that will make managing their condition more effect, easier, and perhaps more affordable. Synlogic's efforts have drawn their attention and raised hopes.
Just before Thanksgiving Jerry Vockley presented the latest data to a metabolism conference meeting in Australia. There were only 8 patients in this group of a phase 2 trial using the original version of the company's lead E. coli product, SYNB1618, but they were intensely studied. Each was given the probiotic and then a challenge meal. Vockley saw a 40% reduction in Phe absorption and later a 20% reduction in mean fasting Phe levels in the blood. The product was easy to use and tolerate.
The company also presented early results for SYNB1934, a follow on version that further genetically tweaked the E. coli to roughly double the capacity to chop up the target proteins. Synlogic is recruiting patients for studies to determine the best dosing, which they are planning for next year.
“It's an exciting approach,” says Lex Cowsert, Director of Research Development at the National PKU Alliance, a nonprofit that supports the patient, family, and research communities involved with PKU. “Every patient is different, every patient has a different tolerance for the type of therapy that they are willing to pursue,” and if it pans out, it will be a welcome addition, either alone or in combination with other approaches, to living with PKU.
Author's Note: Reporting this story was made possible by generous support from the National Press Foundation and the Fondation Ipsen. Thanks to the people who so generously shared their time and stories in speaking with me.
In Ethiopia, Samuna’s three donkeys help her transport produce to market and to collect the water essential to her family, neighbours and livestock. Donkeys are more endangered than people realize, experts say.
“That's the reason why some breeds begin to disappear because humans were not really interested in having that specific breed anymore,” Gambini says. Nonetheless, in Africa, India and Latin America millions of rural families still rely on these hardy creatures for agriculture and transportation. And the only two wild donkey species—Equus africanus in Africa and Equus hemionus in Asia—are also dwindling, due to losing their habitats to human activities, diseases and slow reproduction rates. Gambini’s team wanted to create a way to preserve the animals for the future. “Donkeys are more endangered than people realize,” he says.
There’s much more to donkeys' trouble though. For the past 20 or so years, they have been facing a huge existential threat due to their hide gelatin, a compound derived from their skins by soaking and stewing. In Chinese traditional medicine, the compound, called ejiao, is believed to have a medicinal value, so it’s used in skin creams, added to food and taken in capsules. Centuries ago, ejiao was a very expensive luxury product available only for the emperor and his household. That changed in the 1990s when the Chinese economy boomed, and many people were suddenly able to afford it. “It went from a very elite product to a very popular product,” says Janneke Merkx, a campaign manager at The Donkey Sanctuary, a United Kingdom-based nonprofit organization that keeps tabs on the animals’ welfare worldwide. “It is a status symbol for gift giving.”
Having evolved in the harsh and arid mountainous terrains where food and water were scarce, donkeys are extremely adaptable and hardy. But the Donkey Sanctuary documented cases in which an entire village had their animals disappear overnight, finding them killed and skinned outside their settlement.
The Chinese donkey population was quickly decimated. Unlike many other farm animals, donkeys are finicky breeders. When stressed and unhappy, they don’t procreate, so growing them in large industrial settings isn’t possible. “Donkeys are notoriously slow breeders and really very difficult to farm,” says Merkx. “They are not the same as other livestock like sheep and pigs and cattle.” Within years the, the donkey numbers in China dropped precipitously. “China used to have the largest donkey population in the world in the 1990s. They had 11 million donkeys, and it's now down to less than 3 million, and they just can't keep up with the demand.”
To keep the ejiao conveyor going, some producers turned to the illegal wildlife trade. Poachers began to steal and slaughter donkeys from rural villages in Africa. The Donkey Sanctuary documented cases in which an entire village had their animals disappear overnight, finding them killed and skinned outside their settlement. Exactly how many creatures were lost to the skin trade to-date isn’t possible to calculate, says Faith Burden, the Donkey Sanctuary’s director of equine operations. Traditionally a poor people’s beast of burden, donkey counts are hard to keep track of. “When an animal doesn't produce meat, milk or eggs or whatever edible product, they're often less likely to be acknowledged in a government population census,” Burden says. “So reliable statistics are hard to come by.” The nonprofit estimates that about 4.8 million are slaughtered annually.
During their six to seven thousand years of domestication, donkeys rarely got the full appreciation for their services. They are often compared to horses, which doesn’t do them justice. They’re entirely different animals, Burden says. Built for speed, horses respond to predators and other dangers by running as fast as they can. Donkeys, which originate from the rocky, mountainous regions of Africa where running is dangerous, react to threats by freezing and assessing the situation for the best response. “Those so-called stubborn donkeys that won’t move as you want, they are actually thinking ‘what’s the best approach,’” Burden says. They may even choose to fight the predators rather than flee, she adds. “In some parts of the world, people use them as guard animals against things like coyotes and wolves.”
Scientists believe that domestic donkeys take their origin from Equus africanus or African wild ass, originally roaming where Kenya, Ethiopia and Eritrea are today. Having evolved in the harsh and arid mountainous terrains where food and water were scarce, they are extremely adaptable and hardy. Research finds that they can go without water for 72 hours and then drink their fill without any negative consequences. Their big jaws let them chew tough desert shrubs, which horses can’t exist on. Their large ears help dissipate heat. Their little upright hooves are a perfect fit for the uneven rocky or other dangerous grounds. Accustomed to the mountain desert climate with hot days and cold nights, they don’t mind temperature flux.
“The donkey is the most supremely adapted animal to deal with hostile conditions,” Burden says. “They can survive on much lower nutritional quality food than a cow, sheep or horse. That’s why communities living in some of the most inhospitable places will often have donkeys with them.” And that’s why losing a donkey to an illegal skin trade can devastate a family in places like Eritrea. Suddenly everything from water to firewood to produce must be carried by family members—and often women.
Workers unloading donkeys at the Shinyanga slaughterhouse in Tanzania. Fearing a future in which donkeys go extinct, scientists have found ways to cryopreserve a donkey embryo in liquid nitrogen.
TAHUCHA
One can imagine a time when worldwide donkey populations may dwindle to the point that they would need to be restored. That includes their genetic variability too. That’s where the frozen embryos may come in handy. We may be able to use them to increase the genetic variability of donkeys, which will be especially important if they get closer to extinction, Gambini says. His team had already created frozen embryos for horses and zebras, an idea similar to a seed bank. “We call this concept the Frozen Zoo.”
Creating donkey embryos proved much harder than those of zebras and horses. To improve chances of fertilization, Gambini used the intracytoplasmic sperm injection or ICSI, in which he employed a tiny needle called a micropipette to inject a donkey sperm into an egg. That was a step above the traditional IVF method, in which the egg and a sperm are left floating in a test tube together. The injection took, but during the incubating week, one after the other, the embryos stopped dividing. Finally, on day seven, Gambini finally spotted the exact sight he was hoping to see. One of the embryos developed into a burgeoning ball of cells.
“That stage is called a blastocyst,” Gambini says. The clump of cells had a lot of fluids mixed within them, which indicated that they were finally developing into a viable embryo. “When we see a blastocyst, we know we can transfer that into a female.” He was so excited he immediately called all his collaborators to tell them the good news, which they later published in the journal of Theriogenology.
The one and only embryo to reach that stage, the blastocyst was cryopreserved in liquid nitrogen. The team is waiting for the next breeding season to see if a female donkey may carry it to term and give birth to a healthy foal. Gambini’s team is hoping to polish the process and create more embryos. “It’s our weapon in the conservation ass-enal,” he says.
