Extra 21st chromosome identified as a cause of Down Syndrome by Jerome Lejeune

1959. Jerome Lejeune was a French human geneticist who worked with Dr. Raymond Turpin at the Hospital Saint-Louis in Paris. Turpin’s hospital practice included patients with Down’s syndrome, and Lejeune took over the responsibility of caring for these patients. He believed that Down’s syndrome must involve some sort of genetic change. By 1954, he began to suspect that individuals living with Down’s syndrome must lack a chromosome.

In order to test this hypothesis, Lejeune used cytogenetic techniques, “prepared karyotypes and examined them through a microscope…he photographed the karyotypes…expecting them to show…the absence of a chromosome. Instead, they showed that Down’s syndrome patients had forty-seven chromosomes rather than forty-six” (Kevles, 1985, p.247). In 1959, Lejeune published his results in the Comptes Rendus of the French Academy of Sciences.

Prenatal testing generally screens for genetic abnormalities, including Down's Syndrome, which may lead to aborted fetuses, and less children born with genetic abnormalities.

-Erna Kurbegovic

  • Kevles, D. (1985). In the Name of Eugenics: Genetics and the Uses of Human Heredity. Berkeley: University of California Press.

Extra 21st chromosome identified as a cause of Down Syndrome by Jerome Lejeune

1959. Jerome Lejeune was a French human geneticist who worked with Dr. Raymond Turpin at the Hospital Saint-Louis in Paris. Turpin’s hospital practice included patients with Down’s syndrome, and Lejeune took over the responsibility of caring for these patients. He believed that Down’s syndrome must involve some sort of genetic change. By 1954, he began to suspect that individuals living with Down’s syndrome must lack a chromosome.

In order to test this hypothesis, Lejeune used cytogenetic techniques, “prepared karyotypes and examined them through a microscope…he photographed the karyotypes…expecting them to show…the absence of a chromosome. Instead, they showed that Down’s syndrome patients had forty-seven chromosomes rather than forty-six” (Kevles, 1985, p.247). In 1959, Lejeune published his results in the Comptes Rendus of the French Academy of Sciences.

Prenatal testing generally screens for genetic abnormalities, including Down's Syndrome, which may lead to aborted fetuses, and less children born with genetic abnormalities.

-Erna Kurbegovic

  • Kevles, D. (1985). In the Name of Eugenics: Genetics and the Uses of Human Heredity. Berkeley: University of California Press.