An angiotensin-1 converting enzyme polymorphism is associated with allostatic load mediated by C-reactive protein, interleukin-6 and cortisol. — ME/CFS Atlas
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An angiotensin-1 converting enzyme polymorphism is associated with allostatic load mediated by C-reactive protein, interleukin-6 and cortisol.
Smith, Alicia K, Maloney, Elizabeth M, Falkenberg, Virginia R et al. · Psychoneuroendocrinology · 2009 · DOI
Quick Summary
This study looked at whether a specific genetic variation in a gene called ACE affects how people's bodies respond to stress and illness. Researchers measured multiple stress-related markers (inflammation, immune system activity, and cortisol levels) in people with and without ME/CFS. They found that people carrying a particular version of the ACE gene tended to have higher stress responses and more inflammation, suggesting genes may play a role in how severely someone's body reacts to stress.
Why It Matters
Understanding genetic factors that influence stress-response physiology and inflammation could help explain why ME/CFS patients show abnormal immune and neuroendocrine function, and may eventually enable personalized risk stratification or treatment approaches. This research bridges immunology, genetics, and stress biology—three central domains in ME/CFS pathophysiology.
Observed Findings
The T allele of ACE rs4968591 was significantly more common in subjects with high allostatic load (67.5%) compared to low allostatic load (49.3%).
Carriers of the T allele showed elevated interleukin-6 levels (p=0.04 trend).
Carriers of the T allele showed elevated C-reactive protein levels (p=0.01 trend).
In females, the T allele was associated with lower urinary cortisol levels (p=0.03).
The association between ACE polymorphism and allostatic load remained significant after adjusting for age, sex, BMI, and fatigue status.
Inferred Conclusions
The ACE gene variant rs4968591 influences allostatic load through increased inflammatory markers (CRP, IL-6) and altered cortisol metabolism.
The T allele may affect transcription factor E2F1 binding at the rs4968591 locus, altering ACE expression or regulation.
ACE may play a role in bidirectional communication between the nervous and immune systems during stress response.
Remaining Questions
Does the ACE polymorphism directly cause higher allostatic load, or is the association mediated by other genetic or environmental factors?
How does the T allele variant affect ACE protein function, expression levels, and interaction with E2F1?
What This Study Does Not Prove
This study does not prove that the ACE gene variant *causes* ME/CFS or high allostatic load; it only shows association in a cross-sectional sample. It does not establish mechanism (how the variant alters ACE function or E2F1 binding) and cannot determine whether the genetic effect is primary or mediated by other factors. Findings are also limited to Caucasian populations and may not generalize to other ethnic backgrounds.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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