Yale team finds order amidst the chaos within the human genome

Yale researchers studying the human genome say they can now tell how much "mom" and how much "dad" is genetically active in each of us.

These gender-specific markers may not determine which parent can take credit — or the blame — for the successes or shortcomings of their offspring; however, they could help explain differences in human populations.

"We can now track the relative genetic contribution of mom and dad," said Gerstein.

All human beings are born with two copies of the genome — one from the mother and one from the father. However, sometimes only one of the copies, or alleles, ends up being biologically active for a particular gene. Based on an analysis of the massive amounts of data generated by the ENCODE project, Yale researchers observed this occurs 10 to 20 percent of the time. Researchers did not analyze the functions of these maternal and paternal specific genes and regulatory networks. However, they did note that these "gender-specific" networks tend to be evolving more rapidly than other networks.

"Perhaps, they account for the differences we see among individuals," Gerstein said.

Fossil DNA resurrected in contemporary human genome

Among the oddities turned up during the exploration of the human genome are pseudogenes — stretches of fossil DNA, evolutionary remnants of an active biological past. Yale researchers using sophisticated data mining and statistical models have discovered that many of these genes may not be quite dead after all, as they report in the journal Genome Biology.

These ancient genes no longer code for proteins that carry out life's functions. However, the Yale team shows many of them are resurrected to produce non-coding RNAs, which scientists now know are crucial to the activation and silencing of protein-coding genes throughout the genome.

"This is another example of nature not wasting resources, a story we see repeated time and time again throughout the 3 billion letters of our genome," said Gerstein, senior author of the paper.

The existence of pseudogenes illustrates how human evolution may have worked. The pseudogenes have been inherited from functional ancestors but rendered obsolete via a variety of genetic mechanisms. This is an ongoing procedure, and some pseudogenes could have "died" relatively recently in human history, Gerstein's team found. However, at the same time, some pseudogenes may have been resurrected and harbored an ability to produce tiny RNAs, some of which may have regulatory activity in an advantageous way. As a result, they remain preserved in the genome, note the scientists.

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