A mother whose son has Down Syndrome has penned an emotional letter over the fact he was deliberately excluded from a classmate's birthday party.

The Facebook post said birthday invitations were delivered to the entire 22-student class, except for her son Sawyer.

Jennifer Engele, who describes her child as funny, with an "infectious laugh," feels the decision was made because of his condition – and because the other mother doesn't understand it.

"I know if you knew more about Down Syndrome you wouldn’t have made this decision. I am not mad at you," she wrote.

"People with Down Syndrome want the same things that you and I want. They want to have close relationships, they want to feel love, they want to contribute, they want to have meaningful lives, and they want to go to birthday parties. It may be more difficult at times to understand my child. But the laughter and love that you share doesn’t need interpretation."

Engele, who lives in Langley, B.C., goes on to say that before having her son, she was scared and misinformed about Down Syndrome, and was worried that other children wouldn't connect with him.

She said instead of excluding her son from the party, the other mother could have used the occasion as a reason to teach her child about inclusion.

"They will remember the time that their parent said to them, it’s not OK to leave someone out because of their disability, race, or gender," she wrote.

The Langley mother said in the wake of what's happened, she is committing to advocating more for her son, and wants to educate his class – to clear up any misconceptions.

"Please know that I am here to talk if you would like," she wrote to the other mom.

"I may be a mama bear but I am not a scary person. I recognize that we all make mistakes and at the end of the day, I think we both could have done better."

Since penning the letter on the social media site, Engele said her son has now been invited to the party.

In a follow up post, she thanked the people who shared her story online -- and said she's received an outpouring of support from parents who have gone through a similar situation. She’s urging all parents to think more about inclusion, for the sake of kids that might be left out.

“I have a feeling that Sawyer will have a very busy social calendar next year,” she said.

For more information about Down Syndrome, visit the Down Syndrome Research Foundation website.