A mother diagnosed with Down syndrome at the age of 23 says people “don’t believe” she has the condition.
Ashley Zambelli discovered she had Mosaic Down Syndrome in February 2023 after a genetic test revealed she had an extra chromosome.
Growing up, she says she struggled with a dislocated knee, jaw problems that affected her movements, and a high heart rate.
Doctors didn’t put the problems into context until they examined her reproductive history.
They noted that three of their six pregnancies were diagnosed with Down syndrome, which is unusual for someone so young, Ashley said.
Doctors then performed genetic testing and found that she had mosaic Down syndrome, or mosaicism — a rare condition that results in an extra copy of chromosome 21.
Ashley, a homemaker from Macomb Township in Michigan, USA, said: “People say, ‘You don’t look like you have it.'”
“Even I was very incredulous. I didn’t know it existed.
“Many people associate it with a facial disability, but having a mosaic disease means it’s not always visible to the eye.”
When Ashley was born, she had no traits associated with Down syndrome, she said.
But from the age of 12, her kneecaps “constantly” slipped and she had problems with comprehensive learning at school.
“The test administration was terrible,” she said.
“I had jaw dysfunction, my kneecaps were constantly dislocated and my shoulder was permanently out of socket.”
“Besides, my heart was always racing. I was constantly out of breath.”
It took her until she was 23 weeks pregnant with her third child, Katherine, who was diagnosed at 14 weeks, to see the connection.
Ashley had suffered a miscarriage back in 2019 and doctors had determined the baby had Down Syndrome.
In December 2020, she gave birth to her first child, Lilian, two, who also has Down syndrome.
Their second daughter, Evelyn, who was born in December 2021, does not have this genetic condition.
Ashley said: “They hadn’t seen anyone with three confirmed cases of Down syndrome.
“They said I was very young — so they figured there must be something else.”
Her mosaic Down syndrome gives her a 50 percent chance of having children with an extra chromosome.
Ashley said, “I was very happy to find out.”
The mother-of-three, who doesn’t have the facial features of a person with Down syndrome, now has an explanation for her troubles.
She has deep-set ears, low muscle tone, a jaw disorder, short-term memory problems, and inappropriate sinus tachycardia — meaning she often has a heart rate in excess of a hundred beats per minute.
She said she often finds it difficult to pick up on most humor and is able to say things without realizing they might be offensive.
Ashley, who lives with her husband Taylor Doyle, 28, a restaurant worker, wants to encourage others to get genetically tested.
She said, “People mustn’t see it as a bad thing.”
“It’s a tool to be prepared.”
She also hopes to create a community for people with mosaic Down Syndrome.
What is Down Syndrome?
DOWN syndrome is when you are born with an extra chromosome.
This usually happens randomly, due to a change in the sperm or egg before you are born.
People with Down syndrome have some degree of learning disability — however, some are more independent than others.
In almost all cases, Down syndrome does not run in families.
The chance of having a child with this condition increases with age, but anyone can have a child with it.
Mosaicism, or mosaic Down syndrome, is diagnosed when there is a mixture of two cell types.
Some have the usual 46 chromosomes, others 47.
Cells with 47 chromosomes have an extra chromosome 21.
Mosaicism is usually described as a percentage. Typically, 20 different cells are analyzed in a chromosome study.
A baby is said to have mosaic Down Syndrome if:
- Five of the 20 cells have the typical number of 46 chromosomes
- The other 15 have a total of 47 chromosomes due to an extra chromosome 21
Since the percentage of cells with an extra chromosome is 15 out of 20, the baby would have a 75 percent mosaicism level.
Babies born with mosaic Down syndrome can share the same characteristics and health problems as babies born with trisomy 21 or translocation Down syndrome.
However, it is possible for babies to have fewer features of the syndrome than babies with other forms.
Source: NHS and Stanford Medicine