It’s not trendy, and it’s definitely not a spelling due to lack of education. My parents are both medical doctors and named me Katlyn. It’s a traditional Irish spelling, which is part of my ancestry. I like the spelling of my name. It puts a unique, Irish spin on a name that became overly used shortly after I was born in 92. Ps this Katlyn just graduated law school so I have, in fact, graduated first grade.