Mom Had Three Kids with Down Syndrome. Then She Discovered She Has It, Too (Exclusive)

A mom of three discovered that she shares more than just DNA with her three kids — she shares their specific genetic mutation, too.

TikTok creator Ashley Zambelli, 23, went viral after she discovered that not only would she be having a third baby with trisomy 21 — also known as Down syndrome — but she herself had tested positive for the mutation. In a series of videos posted to her TikTok account, the mom of three shared her shocked reaction.

In one video, Zambelli writes, "My geneticist SHOCKED I'm having a baby with trisomy 21 for the 3rd time."

Across her videos, Zambelli shares that she has three children, two of whom have tested positive for trisomy 21. Zambelli experienced a pregnancy loss with a third baby who also tested positive for the mutation. When her geneticist noticed that she was having so many babies with this specific genetic mutation, Zambelli was prompted to get tested herself.

"Finding out I was pregnant with another baby that has trisomy 21 was definitely a shock to all of us," Zambelli tells PEOPLE exclusively. "It's not unheard of to conceive one to two since Down syndrome is, as far as we know, usually caused by a random failed separation of chromosomes during mitosis. But to have more than one or two? That's when this might not be a 'random' mutation."

Zambelli is mom to three young girls, Lillian, Evelyn, and Katherine.

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"Our oldest daughter Lillian has trisomy 21 and we can't wait to see [her and her sibling] grow up together, including our second daughter, Evelyn, who does not have Down syndrome. We are also very excited to see the person Evelyn grows to become since there's just something special about having siblings with Down syndrome."

Asked what inspired her to get herself genetically tested, Zambelli explains that it was actually her OB/GYN that came up with the idea. "She is the one who informed me that it's pretty rare to conceive a child with Down syndrome three times and wrote me a referral to a geneticist to see if I had a chromosomal abnormality."

Once Zambelli was tested, it came back positive for mosaic Down syndrome, or trisomy 21 mosaicism/mosaic trisomy 21.

According to the Stanford Children's Hospital, this form of Down syndrome is diagnosed when there's a mixture of two types of cells. Some have the usual 46 chromosomes and some have 47, which are the ones with the extra chromosome 21 that defines trisomy 21. Although this can cause babies born with mosaic Down syndrome to have similar features to babies with Down syndrome, it is also possible to have few features.

"When I got the call [with the diagnosis], I was happy! I've always had some miscellaneous complications throughout my life that never made sense to doctors, but now they do," Zambelli tells PEOPLE.

Although her kids are too young to understand their diagnoses, her friends and family were happy and supportive of Zambelli. "My friends and family were very surprised with my diagnosis...everyone was very happy for me and supportive."

In her TikTok videos, Zambelli strives to create an educational platform where she can spread awareness about the genetic mutation. "TikTok has been such an amazing community to be in for spreading awareness of Down syndrome and the three forms of it — trisomy 21, mosaic, and translocation," she says. "All I can do is present the facts, keep spreading awareness, and hope to see a change."

As for the hardest part of her journey? "Encountering some people within the Down syndrome community. There have been a few who do not take me seriously and make me feel as if I need to prove my condition to them," the mom revealed.

"The stigma around Down syndrome unfortunately exists in our own community. I'm hoping that will change soon for the better."