FWIW my sister didn't exhibit obvious symptoms until early 40s.
I'm 40, and all my paternal family, siblings, a nephew and cousin feature some symptoms of hht, many are undiagnosed. My sisters have had diagnoses although not DNA tests AFAIK.
I have an appointment with the Family History Unit of the local Genetics facility, in early Jan. As I exhibit few symptoms, except mild aneamia, I'm unworried, but I need to know if my children should be screened.