The mom of a little girl with Down syndrome battled for doctors to pay attention to her unusual side effects — leading to a scientific breakthrough

• Austin Carrigg knew something was wrong when her toddler, who has Down syndrome, wasn't developing.
• Doctors dismissed her concerns over and over, even when Melanie needed emergency care.
• Melanie was finally diagnosed with ketotic hypoglycemia, and Carrigg published research on the potential link.

Austin Carrigg knew her daughter Melanie would have health problems. Carrigg and her husband had committed to adopting a child with special needs, and Melanie's included Down syndrome, deafness, and a congenital heart defect. 

The couple's older son has a rare disorder, so they thought: "If we could parent him, anything this throws at us, we'll be fine," Carrigg, who now lives outside of Washington, DC, told Insider. 

Two weeks after bringing newborn Melanie home from the neonatal intensive care unit, she went into heart failure and needed open-heart surgery. Again, Carrigg thought things could only go up from there.

"If I can get past this open-heart surgery, the rest of her life is going to be fine," Carrigg said she thought. "I didn't know what was to come." 

What came was several years fighting the medical system for answers about her daughter's lack of development, only to get told over and over it was just Down syndrome. Carrigg eventually found her answer and became a published author in medical literature, advancing science along the way. 

She's speaking out to urge other parents to listen to their guts when it comes to their children's health. 

"We have so many instances where moms and dads say, 'Something's wrong with my child,' and people say, 'No, everything's fine,'" Carrigg said. "We have to understand if something is wrong and that feeling doesn't go away, maybe it's worth the second opinion." 

Even a medical emergency didn't prompt clinicians to dig deeper, Carrigg said 

Developmental scales for Down syndrome note that most children with the condition can stand while holding onto something around age 1. But by age 2, Melanie couldn't even hold her head up or sit up. 

"Something was very wrong," Carrigg said, so she took Melanie to a developmental pediatrician. "He walked in the door — like only half his body — and he said, 'She's never gonna walk, she's never gonna talk, I don't need to see you again, you can check out at the front desk.' And he left." 

Over the next year, Melanie learned to sit and hold her head up, but only with the help of intensive physical therapy. By 3, she couldn't stand and wasn't growing. "We kept pumping her full of calories, but she just wasn't growing, and nobody couldn't figure out why." 

Then, during a trip to visit family in Arizona, Melanie became lethargic, threw up, and resisted her dad's embrace. By the time they got to the ER, the little girl was in a coma.

She spent five days in the hospital, where tests revealed dangerously low blood sugar and ketones in her blood. At one point, a routine fasting test led to Melanie crashing — and clinicians needing to put an IV in her jugular to revive her immediately. 

While Down syndrome is linked to a range of potential complications, including heart defects and immune disorders, the condition alone would not explain tanking blood sugar. 

And still, Melanie was discharged with no explanation. 

"And after all of that was done, the team said, 'We have no idea what's wrong. You need to get on a plane and go home," Carrigg remembers. 

A geneticist finally led to some answers

At home, doctors continued to insist everything was fine, that these things "just happen." 

"Finally," Carrigg said, "I got a resident on the phone, and I think at that moment I just lost it. I'm like, 'You know, if something happens to my daughter, we'll hold you responsible.' And she promptly got us a referral to a geneticist and we got to a metabolics team." 

Tests revealed she has chromosomal deletion that affects how the body synthesizes sugar. Melanie, now 9, is the first known patient with that particular deletion presented in that way, Carrigg's later research reported. It caused ketotic hypoglycemia, which describes low blood sugar with ketosis.

The first-line treatment for KH: cornstarch, a long-acting carbohydrate that slowly burns off sugar. Melanie consumed it mixed with water through her G-tube as well as mixed with formula.

Giving her energy her body could process "was like watching her wake up," Carrigg said. "It felt very much like I had a baby to all of a sudden she's running and playing and telling me 'no.' She's demanding, but sweet and kind. She cares about everybody, and if I cry, she cries. And just to think I could have missed all of that." 

Carrigg prompted research showing there may be a link between Down syndrome and ketotic hypoglycemia 

In online forums for parents of children with Down syndrome, Carrigg connected with another mom whose kid also had ketotic hypoglycemia. "That's weird," she thought, "what are the odds of that?" The moms started noticing others post about symptoms in line with the condition. 

So Carrigg called Ketotic Hypoglycemia International. "I said, 'I think this is something,' and they listened," Carrigg said. In five days, Carrigg and the organization conducted a survey including 140 parents of children with Down syndrome worldwide. They found about 7% either had ketotic hypoglycemia or symptoms warranting that diagnosis. 

By comparison, only 1% of people with Down syndrome develop leukemia, but that link is widely-discussed in the community, Carrigg said. It's unclear how common ketotic hypoglycemia is in the general population since it's a diagnosis of exclusion and it's under-researched. 

The team published their results in the medical journal JIMD Reports, a publication of the Society for the Study of Inborn Errors of Metabolism. Carrigg served as a co-author. She's now the vice president of disability research and policy at Ketotic Hypoglycemia International, in addition to running a national nonprofit for military families.

Researchers' next steps will be to try to understand what might be underlying both conditions. Carrigg and others have already started their next study, out of Denmark, where KHI is based.  

"I think that's proof that patients and caregivers can bring a lot to the table, even if they don't have a background in medicine," she said. "I'm really proud of the fact that we kind of turned the tables on what it means to be a citizen scientist and to be involved in research, because this isn't how it typically plays out."