"The NIH team began sleuthing. To its surprise, the woman’s white blood cells no longer had the faulty CXCR4 mutation, although other cell types still carried it. Examining the chromosomes in her apparently normal white blood cells, they found an anomaly: One copy of chromosome 2 was about 15% shorter than the other copy. Whole-genome sequencing revealed that it had become scrambled and lost a chunk that included the defective CXCR4 and 163 other normal genes.
The explanation seems to be chromothripsis, a phenomenon discovered only 4 years ago in a leukemia patient and occasionally seen in other cancers. A chromosome somehow shatters during cell replication, then reassembles with the pieces in a different order. Presumably, the cells typically die as a result of this damage, Murphy says. If the cell survives, the scrambled genes may contribute to cancer.
In this case, however, the chromosome shattering seems to have occurred in a blood stem cell, which then replicated to give her a supply of normal white blood cells. The missing copy of CXCR4 also appears to explain why the cells now constitute all of her white blood cells, the NIH researchers say. They showed that transplants of stem cells lacking one copy of CXCR4 engraft better in mice than stem cells with two normal copies or a normal copy and the WHIM version, they report online today in Cell."
http://news.sciencemag.org/biology/2015/02/shattered-chromosome-cures-woman-immune-disease?utm_source=facebook&utm_medium=social&utm_campaign=facebook
No comments:
Post a Comment