Kourtney Kardashian turns 36 on Saturday (18th April) and her family have wished her a Happy Birthday on social media. They are throwing a party at one of the family's favourite clubs, 1OAK in Las Vegas, but one of her siblings may not be able to attend. Khloe will reportedly be absent from the occasion as she is launching a group messaging app, Regroupd.

Khloe KardashianKhloe Kardashian may be missing her older sister's birthday party, according to reports.

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30-year-old Khloe is in Coachella where she will be entertaining more than a hundred celebrity guests and providing them with tutorials on how the new app works. According to reports in TMZ, Khloe, who is fronting the app, has rented out a huge house in the desert for the occasion. Guests will be able to relax by the pool and enjoy burgers and ice cream from two of the food vans on standby. Kendall and Kylie Jenner have also joined her, according to Tweets on Regroupd's feed. So it is possible the sisters will fly out to Las Vegas in time for the party later on. 

The entire family have wished Kourtney Happy Birthday on Instagram with Khloe posting a lengthy caption along with a picture montage of the two together but included a message to all her sisters. "My life would be meaningless without ALL of you," Khloe wrote. "So with every single birthday I am more and more appreciative that we get to spend another year together only strengthening our bond as soulmates every single one of us."

Kourtney's mother, Kris Jenner, also posted a photograph on Instagram. The picture was of Kris holding Kourtney as a baby and Kris described herself as "obsessed" with her eldest daughter from "the moment you were born". 

"When you were born I realized what true love really is," Kris added. "You are the most amazing Mom I have ever known, the best daughter, friend, sister, and partner and you are loyal to a fault... You are the most beautiful person inside and out and I am so blessed and honoured to be your Mom and we are all better because we get to share life with you."

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Happy birthday to one of the most monotone chicks I've ever met. It's one of my favorite things about you!! Bible! Every single day I become more and more thankful for how many permanent God given best friends I have in my life. Kourt you are the yin to my yang, the Siegfried to my Roy, the Lucy to my Ricky, The Thelma to my Louise, the Wayne to my Garth, the Posh to my David, the sugar to my spice, the icing to my cake. I cannot express how much I love you, respect you, admire you. You inspire me every day. I couldn't ask for a better big (little) sister. My life would be meaningless without ALL of you. So with every single birthday I am more and more appreciative that we get to spend another year together only strengthening our bond as soulmates every single one of us.

A photo posted by Khloé (@khloekardashian) on