When Kyra Pringle posted a photo of her smiling two-year-old daughter Mariah on Instagram, she never imagined it would become the subject of cruel internet vitriol.

Mariah, from South Carolina, USA, was born with a Chromosome 2p duplication syndrome – a condition that affects development, motor skills and appearance and significantly limits life expectancy.

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To celebrate her daughter surviving past infancy, Ms Pringle snapped and shared a photo of Mariah smiling while enjoying her second birthday party, which then went viral for all the wrong reasons.

Kyra Pringle with her daughter Mariah. Photo: WCBD

When Ms Pringle saw her daughter’s face featured in memes comparing her to “a leprechaun” and calling her ugly, she knew she had to speak out.

“The smile that you guys think is funny or the smile that you guys are comparing to a leprechaun,” Ms Pringle told local television station WCBD.

“The things you guys are saying about my child, she’s not a monster, she’s real.”

Mariah’s grandmother Linda Pringle also weighed in, lambasting the trolls for their cruel sense of humour.

“If you’re out there and you’re doing these things, and you think that it’s funny, it’s not funny,” she said.

“This is actually a human being, this is a child, this is a baby.”