Systemic Lupus Erythematosus (SLE) can start at any age, but it is most commonly diagnosed in women of childbearing age, between the ages of 15 and 44. However, it can also occur in children and older adults. The exact cause of SLE is not known, but it is thought to be due to a combination of genetic, environmental, and hormonal factors. It is important to note that lupus can present differently in different individuals, and the symptoms can range from mild to severe. If you have concerns about lupus or any other health condition, it is best to consult with a healthcare professional.