Common Questions About Rare Diseases

"I knew something was not right when Azeneth wasn’t making any effort at crawling, standing, or walking. And I noticed her shaking before she fell asleep."
- Brenda Saldivar, mother of a Caroline School student with Rett syndrime

Where symptoms or functional difficulties have no easy diagnosis, a “rare disease” may be responsible. This post is dedicated to Rare Disease Day, observed on February 28, or February 29—a rare day—in Leap Years.

What Makes a Disease “Rare”?

A “rare disease” is a disorder or illness that affects 0.065 percent or fewer of the total population. “Rare” does not mean “has negligible effect.” Over 300 million people worldwide live with one rare-disease condition or another. Add in their families, and that makes an estimated one-billion-plus people whose lives are affected.

The numbers are high because the variety of rare diseases is high: over 7,000 are known. Most experts sort them into four categories:

  1. Non-genomic, caused by factors unrelated to genes or chromosomes. Examples: mesothelioma (cancer from asbestos exposure); anemia from vitamin B12 deficiency.
  2. Multifactorial, ccaused by a combination of two or more factors, usually genetic and environmental. Two of our 2025 Walk With Me ambassadors have multifactorial rare diseases: Aidan with Lennox–Gastaut syndrome (a severe form of epilepsy), and Theo with Hypoplastic Left Heart Syndrome (an underdeveloped left side of the heart, which causes problems with breathing and circulation).
  3. Chromosomal, caused by abnormal chromosomes or by having more or fewer chromosomes than normal. Examples: DiGeorge syndrome; Patau syndrome; Triple X syndrome. Down syndrome is a chromosomal disorder, but not a rare one.
  4. Single-gene, caused by one specific gene mutation.

Despite the scale of rare diseases, only about 5 percent have official treatments—and many go undiagnosed or misdiagnosed.

How Can So Many Doctors Get It Wrong?

Most of the better-known rare diseases are single-gene: Fragile X syndrome; Sickle cell disease; Cystic fibrosis, with over 100,000 cases worldwide; Rett syndrome, a neurodevelopmental disorder affecting mostly females, usually diagnosed in early childhood after a regression in motor, cognitive, and language skills.

Unfortunately, even these better-known disorders are often misdiagnosed.

"I kept telling Azeneth’s pediatrician and others what was happening—and they kept telling me that I just had a “lazy baby,” or that the shaking was normal “involuntary movement.” It was not until she was 18 months old that the pediatrician got concerned. And it was only after an EEG that her shaking was diagnosed as seizures. Even then, her symptoms were blamed on autism and ADHD."

It’s understandable that many doctors don’t recognize rare diseases. With thousands of different conditions, each affecting a relatively small demographic, there just aren’t sufficient resources to train doctors in everything. But that doesn’t change the frustration and pain felt by individual families.

"Azeneth wasn’t retaining what was being taught in ECI therapies; and her first seizure medicine—prescribed without an exact diagnosis—did more harm than good. Finally, after several trips to the ER and my insisting on genetic testing, she was diagnosed with atypical Rett syndrome."

What Do We Do?

Finding rare-disease treatment can be discouraging, to say the least. But even when it seems you’ve tried everything and nobody listens anyway, there are actions you can take.

  1. Trust your own instincts. If you’re uncomfortable with a diagnosis, insist (and keep insisting) on a second or third opinion.
  2. Consult a nonprofit—such as your nearest Easterseals affiliate—that offers general disability-support services (see ESGH’s Early Childhood Intervention and Children's Therapy resources).
  3. Join a patient advocacy group. There’s strength in numbers, even where patients number only a few thousand.
  4. Learn all you can on your own.
  5. Don’t be afraid to ask for everyday help. Being a special-needs parent is a 24/7 job (whether or not you also work for income). You need all the respite time you can get.
  6. Accept and appreciate your child/situation/health. Learn to see the blessings, not just the burdens.

"I truly believe that Rett children understand more than they can communicate. If you take the time to know them, you will find that they are smart and funny."

-Katherine Swarts, Digital Content Writer, BridgingApps, a program of Easter Seals Greater Houston