Down Syndrome Timeline and Key Milestones

1866: First described by Dr. John Langdon Down; illness referred to as a “syndrome” because individuals show variable symptoms and severities.
1932: Nondisjunction, a chromosomal mechanism, first suggested as the cause of Down syndrome (DS).
1933: Study discovers a link between maternal age and occurrence of DS.
1946: Life expectancy of individuals with DS reported as 12 years.
1948: First publication describing association of Down syndrome with Alzheimer’s disease.
1959: Dr. Jerome Lejeune discovers that Trisomy 21 (T21) causes the majority (~95%) of DS cases in the US.
1965: World Health Organization (WHO) accepts “Down Syndrome” as the standard term.
1968: DS first detected with amniocentesis (fetal diagnosis technique).
1979: Life expectancy of individuals with DS increases to about 25 years.
2004: Down syndrome linked to gene dosage due to duplication of part or all of chromosome; increased dosage of any single gene can contribute to DS features.
2010: Rosa’s Law signed by Barack Obama removes demeaning terms (e.g., “retardation”) from legislation.
2021: Life expectancy increases to ~60 years; early intervention and specialized therapies support motor and cognitive development; ongoing disparities in health care and care delivery.
Throughout, emphasis on early intervention and specialized therapies to improve motor and cognitive development, with ongoing potential for health care equity improvements.