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The African genome project
非洲基因组计划 (2)
The evolutionary line leading to Homo sapiens diverged 5m-6m years ago from that leading to chimpanzees, and for almost all that time the ancestors of modern humans lived in Africa.
Only about 60,000 years ago did Homo sapiens venture widely beyond the continent, in small bands of adventurers. Most of humanity’s genetic diversity, undersampled though it is, is therefore found in Africa. Unfortunately, that diversity is also reflected in the greater variety of genetic illnesses found there.
The bias in sequencing leads to underdiagnosis of diseases in people of (relatively recent) African descent. Genetic causes of heart failure, such as the one that caused the ultimately fatal collapse of Marc-Vivien Foé, a Cameroonian football player, during a game in 2003, are poorly understood. The variation present in most non-Africans with cystic fibrosis is responsible for only about 30% of cases in people of African origin. This is one reason, along with its relative rarity, that the illness is often missed in black children. Standard genetic tests for hearing loss would not have picked up the Mutambara boys’ variations. And such is the diversity within the continent that tests in some countries would be irrelevant in others. In Ghana HI-GENES found one mutation responsible for 40% of inherited deafness. The same variation has not been found in South Africa.
非洲基因组计划 (2)
The evolutionary line leading to Homo sapiens diverged 5m-6m years ago from that leading to chimpanzees, and for almost all that time the ancestors of modern humans lived in Africa.
Only about 60,000 years ago did Homo sapiens venture widely beyond the continent, in small bands of adventurers. Most of humanity’s genetic diversity, undersampled though it is, is therefore found in Africa. Unfortunately, that diversity is also reflected in the greater variety of genetic illnesses found there.
The bias in sequencing leads to underdiagnosis of diseases in people of (relatively recent) African descent. Genetic causes of heart failure, such as the one that caused the ultimately fatal collapse of Marc-Vivien Foé, a Cameroonian football player, during a game in 2003, are poorly understood. The variation present in most non-Africans with cystic fibrosis is responsible for only about 30% of cases in people of African origin. This is one reason, along with its relative rarity, that the illness is often missed in black children. Standard genetic tests for hearing loss would not have picked up the Mutambara boys’ variations. And such is the diversity within the continent that tests in some countries would be irrelevant in others. In Ghana HI-GENES found one mutation responsible for 40% of inherited deafness. The same variation has not been found in South Africa.
