Two age peaks in the incidence of chronic fatigue syndrome/myalgic encephalomyelitis: a population-based registry study from Norway…, 2014, Bakken+

[Evergreen]

If female susceptibility is due to incomplete X chromosome inactivation it ought to operate at age 15 as well as 35. Unless of course the incomplete inactivation is oestrogen dependent.

Speaking of oestrogen, it does rise in males as well as females during puberty, though not nearly as much, and then stays steady for males, while jumping around a lot for females. That's if this preprint is robust "Estrogen Hormone Is an Essential Sex Factor Inhibiting Inflammation and Immune Response in COVID-19":

 

[Trish]

I assume the suggestion of female hormones playing a role is as a possible predisposing factor for some, though it clearly can't be a necessary factor, since men and post menopausal women can get ME/CFS. And it can't be a key perpetuating factor either, as the menopause is not, as far as I know, a staging post for either worsening or recovery in those whose ME/CFS started before the menopause.

 

[Jonathan Edwards]

I assume the suggestion of female hormones playing a role is as a possible predisposing factor

Yes, it would be a statistical weighting factor, along with some other genes, as per DecodeME and age etc.. For any given set up there will be a risk level and it will be a matter of chance - 1 in 100 or 1 in 40 or 1 in 500, whether you get disease.

 

[OrganicChilli]

I assume the suggestion of female hormones playing a role is as a possible predisposing factor for some, though it clearly can't be a necessary factor

What about pregnancy? I remember a thread where some members reported remission during pregnancy.