It’s a sure bet many of your students are lamenting their height, wondering when or if they’ll ever grow into their feet! Tall and lanky? Blame your genes was the lead story on ABC News in Science, Monday, September 03, 2007. This story illustrates several concepts associated with the methods of science and scientific enterprises, as described in Content Standard G of the National Science Education Standards. It also hits directly on Life Science Content Standard C, grades 5-8:

Hereditary information is contained in genes, located in the chromosomes of each cell. Each gene carries a single unit of information. An inherited trait of an individual can be determined by one or by many genes, and a single gene can influence more than one trait. A human cell contains many thousands of different genes.

The characteristics of an organism can be described in terms of a combination of traits. Some traits are inherited and others result from interactions with the environment. Height is a polygenic trait, meaning many different genes contribute cumulatively to height determination. The trick is to determine which genes are players, how those genes contribute, and how much they contribute to height. Several researchers from the UK, Sweden, Finland, and the U.S. have uncovered a partial answer to these questions. Their published article appears in Nature Genetics. The authors hypothesized the locus of the gene based on previous research involving pygmy mice.

The gene is called “highly mobile group A2,” or HMGA2. In an initial sample of 4,921 people, a pattern emerged where people with two copies of the variant gene tended to be almost 1cm taller than those with no copies of the variant gene. Those with one copy of the variant gene were about 0.4cm taller than those with no copies of the variant gene. In another sample of several thousand more adults and children, the pattern was replicated. The researchers estimate this one gene accounts for perhaps only 0.3% of the height variation in the human population, and that perhaps hundreds of other genes are involved.

According to News in Science, “Interest in ‘height’ genes is spurred by more than idle curiosity, for there could also be a windfall in knowledge about disease. Taller people are statistically more likely to be at risk from some kinds of cancer (prostate, bladder and lung, for instance), which implies that genes that regulate cell multiplication may also play some part in letting cancer cells proliferate.”

Here are some additional resources that are part of the NSDL Middle School Portal collection: Kids Genetics, Mendel’s Experiments, and The Genetic Science Learning Center: The Basics and Beyond.

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