Thames & Kosmos Genetics & DNA handleiding

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Thames & Kosmos

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Handleiding

The History of Down Syndrome

There are about 350,000 people in the United States with Down Syndrome. It is one of the

most common chromosomal abnormalities, and it affects people of all backgrounds,

races, ages, and genders.

Although the condition was recognized in people much earlier, Down Syndrome was

ﬁrst identiﬁed as a unique syndrome in the 19th century by an English doctor named

John Langdon Down, for whom the condition is named. In the middle of the 20th century,

a French physician named Jerome Lejeune discovered that patients with the syndrome

all had 47 chromosomes instead of the normal 46. Later, it was discovered that it was

speciﬁcally the presence of a third 21st chromosome that resulted in Down Syndrome.

Today, people living with the condition are active, contributing members of our

communities. Every year, more and more people with Down Syndrome are graduating

from high school and college, ﬁnding jobs, and living on their own.

The DNA model:

A lot of people worked on it, but only three won the Nobel Prize

By the year 1953, it was already clear that the DNA in

the chromosomes had to be the hereditary material,

and that it therefore contained the program that

shaped the construction of our bodies down to the

tiniest cells, and that deﬁned the color of our hair

or even to some extent the tendency to become a

sports star or a studious bookworm.

But scholars were still stumped by the task of

ﬁguring out the component parts of the threads

and, most of all, by the puzzle of how the

program for life was stored in them. DNA is an

abbreviation of the rather complicated word

deoxyribonucleic acid. Chemists call this kind

of structure a molecule. Molecules are much

smaller than cells — they are the chemical

building blocks of cells, but also of things like

sugar, salt, rubber boots, or the polystyrene

tray in this science kit.

CHECK IT OUT

Cells and Chromosomes | 25

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