The month of April holds a lot of meaning for John Travolta and Kelly Preston, whose late son, Jett Travolta, would have turned 27 on April 13. Their daughter, Ella, has an April birthday as well -- she turned 19 on April 3, one day after National Autism Day, an annual milestone created to honor and spread awareness about the developmental disorder Jett suffered from prior to his death in 2009.

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Jett, in particular, was on Kelly's mind on Friday, April 5, when she shared a black-and-white photo of her and John smiling as they leaned in to kiss Jett on either cheek.

"To my sweet love, Jett… you are in our hearts forever," Kelly captioned the photo, which shows Jett grinning as he rests in a large bed with his mom and dad.

"I send love to all of the beautiful autistic children and the wonderful people who love them," Kelly continued. "May we all shine and grant love and respect to children with special needs 💕 #autismawareness #autism."

Jett died unexpectedly in early January 2009 while vacationing with his family at the Old Bahama Bay Hotel on Grand Bahama Island. He was just 16 at the time and had suffered a seizure that caused him to fall, hitting his head on a bathtub.

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It wasn't until after he died that Kelly and John spoke openly about his autism, epilepsy and asthma, although Kelly revealed in 2003 that he was also diagnosed with Kawasaki Syndrome when he was 2. A common and rarely fatal but potentially series illness, Kawasaki Syndrome can cause damage to blood vessels and can contribute to weakened coronary arteries, according to the American Heart Association.

That same year, John told People he couldn't "imagine what life would be like without" his then 2-year-old son.

"After he was born and cleaned up, I held him for hours while Kelly slept," John said at the time. "When they came to take him away for various tests, I said, 'No, you can't see him today. You'll have to do it another day.' I went a little nutsy."

He sounded similarly smitten when asked about Ella, now 18, and Benjamin, the 8-year-old son he shares with Kelly.

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"She's so amazing and so unlike what you think a teenager, the cliché of a teenager," he told Closer magazine of Ella earlier this year. "She's different, and she's gracious, and she's lovely, she's well-mannered, and she's thoughtful, and it's authentic. It's very old school. She reminds me of an older movie star. Another era. So I'm very proud of her."

Kelly and John first stepped out publicly together in 1990. They eloped soon thereafter in Paris, saying "I do" before a French Scientology minister.