No age limit
syndrome [fms] is known to affect individuals from early childhood [nearly equal frequency in boys and girls] to the elderly.
It can start at any age. In adults, fms is much [7-9 times] more common among females than among males. The most common age for fms is 40-60 years. The prevalence of fms increases with age up to about 70 years, after which it seems to decline.