22q11.2 deletion syndrome is caused by the deletion of a small section of chromosome 22. It results in a cleft palate, heart defects, autoimmune disorders, and more. The symptoms vary wildly and can be accompanied by learning disabilities and mental illness. Cystic fibrosis is caused by a point deletion.
The melody of Happy Birthday to You comes from the song  Good Morning to All , which has been attributed to American siblings Patty Hill and Mildred J. Hill in 1893, although the claim that the sisters composed the tune is disputed.
Factoid The famous song Happy Birthday To You is still in copyright & cannot be used in anyway without a specific license. This song was written and sung by Elfed Hayes and makes a good alternative - check the other variations in case this arrangement is too full.