Genetic diversity may hold clues to modern diseases

GENETIC DIVERSITY in African populations could hold important clues about modern diseases like obesity, high blood pressure and diabetes, according to a US expert.

"Mutations associated with disease in modern populations may have been selectively advantageous in the past," said Dr Sarah Tishkoff from the University of Pennsylvania, who yesterday addressed a conference in Dublin to celebrate 50 years of genetics study at Trinity College Dublin.

Analysing patterns of genetic variation in African populations would help identify genes that allowed ancestral humans to adapt to environmental factors like diet, but that could increase susceptibility to modern diseases associated with lifestyle, according to Dr Tishkoff. So far her work had identified DNA variations among dairy-herding groups in Africa that allowed individuals to digest milk as adults, and she was now looking at traits like height and taste perception in populations around Africa, she said.

DNA variation could help shed light on how Africans and people of African descent metabolise therapeutic drugs, which has a genetic basis, added Dr Tishkoff. "That's really important because most drugs being developed are being looked at in non-Africans," she said. "We really need to characterise genetic variation across diverse ethnic groups."

Variations in African DNA could also provide answers about how humans evolved: "Anatomically modern humans arose in Africa 200,000 years ago, and studying African diversity is crucial if we want to look at human evolution," said Dr Tishkoff.

Delegates also heard about the emerging field of neurogenetics, which looks at how genes affect brain development and function. Trinity psychiatrist Prof Michael Gill stressed the importance of looking at DNA from large groups of patients.

The approach was showing that variations in DNA sequence and structure can be associated with mental illness, he said.

Some common variations contributed a small effect, while rarer changes could have a larger impact in some individuals, said Prof Gill.

"It's emerging that these changes are important in autism and schizophrenia, and they are associated with neuro development, brain wiring and neurochemical function," he said.

The four-day conference finishes today with a public symposium, The Secret of Life: Genetics in the 21st Century. Talks are to be presented by Irish and international experts on personalised genetic readouts, criminal forensics, stem-cell therapies, the origins of HIV, human evolution and genetic modification.

The public lecture series runs today at 11am-6pm at the D4 Hotel Ballsbridge Inn (formerly Jurys) in Dublin. See www.genetics50.org