Some more enlightenment on the genetics of race

A little striped fish is helping scientists solve one of the biggest mysteries in biology - which genes are responsible for differences in human skin, eye and hair colour. The large, international team of scientists have found a gene that makes African zebrafish of a lighter-than-normal colour - and say the same gene helps explain the light-coloured hair, skin and eyes of many Europeans. While they stress they have not found a genetic basis for race, [what is it that they have found, then?] they say just a tiny change in a single amino acid plays a major role in causing the distinctive light European colouring. The gene is called SLC24A5, Keith Cheng of Pennsylvania State University and colleagues said. "Our results suggest that SLC24A5 explains between 25 and 38 per cent of the European-African difference in skin melanin index," the scientists wrote in tomorrow's issue of the journal Science.

Cheng's team was originally looking for genes involved in cancer. They were using zebrafish, a favoured tool of genetic researchers because they are small, reproduce quickly and are well understood. They found a gene that appeared to make some zebrafish "golden" - with lighter-than-usual stripes. Under a microscope, the skin of these fish have smaller, fewer structures called melanophores. In people of European descent, pigment granules called melanosomes are fewer, smaller, and lighter than those from people of West African ancestry. The melanosomes of East Asians fall in between. This suggested gene variations may be responsible and may be similar in vertebrates - which include fish, mice and people.

Scientists know that more than 100 genes are involved in pigment production, so the process is complex. But most of the genes identified so far are found in unusual conditions such as albinism, which causes very light skin and eyes. "...the genetic origin of the striking variations in human skin colour is one of the remaining puzzles in biology," the researchers wrote. But researchers have published several maps of the human genome and made them available to anyone. Cheng's team made use of them. They zeroed on on SLC24A5. Penn State pharmacologist Victor Canfield found that all vertebrates have a version of the gene. They found that one version appears to be the "base" version and is found in most people of African and East Asian descent. Europeans have a mutant version that differs by only a few letters of the genetic alphabet

Source. (The scientific abstract is here)

Comments? Email John Ray

No comments:

Post a Comment

All comments containing Chinese characters will not be published as I do not understand them