Trea­sure trove in Africa’s roots

Re­searchers are plot­ting Africans’ DNA to delve into hu­man­ity’s ear­li­est ori­gins

Saturday Star - - METRO -


ACROSS Africa lies a trea­sure trove that is help­ing in the fight against dis­ease and telling the story of our ear­li­est ori­gins.

This trea­sure is car­ried in the cells of every liv­ing African, but only re­cently have sci­en­tists be­gun un­lock­ing its se­crets.

The dou­ble helix of DNA and Africa have be­come the next fron­tier in ge­netic re­search.

Hu­mans orig­i­nated from Africa, and this makes Africans unique when com­pared to other pop­u­la­tions.

“We (Africans) are the first pop­u­la­tions of modern hu­mans and, by study­ing our DNA, this will in­form what is hap­pen­ing in the other pop­u­la­tions. So, there is a gap in what we know about hu­man ge­netic vari­a­tion and data from Africa can close this gap,” said Dr Michelle Skel­ton of the Univer­sity of Cape Town, who is part of the Hu­man Hered­ity and Health in Africa (H3africa) Ad­min­is­tra­tive Co-or­di­nat­ing Cen­tre.

H3africa is a health and ge­nomics re­search con­sor­tium that spans 32 coun­tries and in­cludes 48 projects. The ini­tia­tive be­gan in 2012.

“The rest of the world is ac­tu­ally pop­u­lated by a sub set of peo­ple who came from Africa and mi­grated out of the con­ti­nent in sev­eral waves from roughly 70 000 years ago,” said Pro­fes­sor Michele Ram­say of Wits Univer­sity, who is also in­volved with H3africa and leads a large, col­lab­o­ra­tive cen­tre in a study on car­diometabolic dis­ease (in­clud­ing obe­sity, hy­per­ten­sion and di­a­betes) across four African coun­tries, with more than 12 000 par­tic­i­pants.

“You can see why the whole world would be in­ter­ested to un­der­stand what as­pects of African ge­net­ics vari­a­tions they see in their pop­u­la­tions.”

Slowly, more and more ge­netic re­search is hap­pen­ing across Africa. At a re­cent con­fer­ence in San Diego in the US sci­en­tists pre­sented their find­ings in what is one of the largest sets of African ge­nomic data avail­able to date.

Re­searchers col­lected and an­a­lysed ge­nomic ma­te­rial from 6 400 in­di­vid­u­als in Uganda, which was then com­bined with that of 7 784 peo­ple from other African coun­tries.

“This study rep­re­sents one of the largest and most com­pre­hen­sive ef­forts to iden­tify ge­netic as­so­ci­a­tions with dis­ease within African pop­u­la­tions, and will pro­vide a roadmap for largescale genome-wide as­so­ci­a­tion stud­ies across the re­gion,” Dr Aye­sha Mo­tala, a leader of the study and pro­fes­sor at the Univer­sity of Kwazulu-natal, told the con­fer­ence.

This re­search has al­lowed some in­sight into the com­plex his­tory of mi­gra­tion in east Africa, which has con­tin­ued for thou­sands of years.

But be­sides fol­low­ing the paths of an­cient mi­gra­tory routes, ge­net­ics is pro­vid­ing in­sight into dis­eases and how they af­fect dif­fer­ent pop­u­la­tions.

“What we want to un­der­stand is the re­la­tion­ship be­tween ge­netic vari­a­tion and dis­ease,” said Ram­say.

“We want to look at the peo­ple who are liv­ing now to un­der­stand how ge­netic vari­a­tion has de­vel­oped over tens of thou­sands of years and how it makes peo­ple more or less sus­cep­ti­ble to par­tic­u­lar dis­eases or traits.”

Some of the dis­eases are old, like malaria and TB in­fec­tions, while oth­ers such as di­a­betes are as­so­ci­ated with obe­sity, a modern-day pan­demic that is be­gin­ning to gain a foothold on the con­ti­nent.

There is a study of how obe­sity is af­fect­ing pop­u­la­tions in west Africa,

This genome chip has been specif­i­cally de­signed for Africa

Dr Michelle Skel­ton UCT DNA re­searcher

east Africa and South Africa.

But work­ing in Africa does have its chal­lenges. There are cul­tural is­sues to deal with, es­pe­cially de­vel­op­ing an ap­pro­pri­ate vo­cab­u­lary to ex­plain ge­net­ics and ge­nomics to com­mu­ni­ties, cul­tural im­pli­ca­tions where blood might have to be taken as part of the study and re­quest­ing con­sent for fu­ture use of data and sam­ples. Policies had to be drawn up to deal with such eth­i­cal is­sues.

Then there is also the lo­gis­tics of deal­ing with dif­fer­ent coun­tries and in­sti­tu­tions. Skills are also a prob­lem and there­fore ca­pac­ity de­vel­op­ment is a pri­or­ity. But ul­ti­mately, the plan is to col­lect more sam­ples across the con­ti­nent.

What will help in analysing large quan­ti­ties of sam­ples in or­der to col­lect ge­netic data is a genome chip that has been de­vel­oped by H3africa.

“This genome chip has been specif­i­cally de­signed for Africa, to de­tect spe­cific ge­netic vari­a­tions that are unique to Africans.

“We will now be able to look at big­ger pop­u­la­tions by just scan­ning the genome us­ing this chip,” said Skel­ton.


THE Klip­drift site in the West­ern Cape where re­searchers found that stone tools re­cov­ered from the com­plex shared sim­i­lar­i­ties with those found at other sites hun­dreds of kilo­me­tres away. |

EX­AM­PLES of stone tools ex­ca­vated from the Klip­drift Shel­ter.

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