Creutzfeldt-Jakob Disease (CJD): Age Distribution and Risk Factors

CJD is a rare prion disease (~1–2 cases/million/year). Age patterns differ by subtype:

Sporadic CJD (sCJD) – 85% of Cases

• Median onset: 65–70 years.
• Range: 40–80+; rare <30.
• Incidence peaks age 70–75.
• No known risk factors; stochastic PrP^C misfolding.

Genetic CJD (gCJD) – 10–15%

• Autosomal dominant PRNP mutations (E200K, D178N, V210I, etc.).
• Earlier onset: often 40s–50s; penetrance incomplete.
• Family history key clue.

Iatrogenic CJD (iCJD) – <1%

• Contaminated neurosurgical instruments, dura grafts, cadaveric hGH/gonadotropin.
• Onset depends on exposure age + incubation (years–decades).

Variant CJD (vCJD) – Zoonotic

• Median onset: 28 years (range 12–74).
• Linked to BSE exposure (dietary, transfusion).
• All clinical cases: methionine homozygous at codon 129.

Risk Factors Summary

Subtype	Age Peak	Key Risk Factor
sCJD	70s	Age, stochastic
gCJD	40s–50s	PRNP mutation
vCJD	20s–30s	BSE dietary exposure, 129MM