In this week's online early edition of Science, a team from the University of Cambridge reports on its identification of a genetic mutation that predisposes people to respiratory infections. Using exome sequencing, the researchers searched the DNA of 35 individuals with primary immunodeficiency who experience recurrent airway infections and found a mutation in the gene PIK3CD shared by several unrelated patients. They then developed a genotyping assay to search for the mutation in an additional 3,000 individuals and discovered that no healthy person carried the mutation. Additional research showed that the mutation causes signaling defects in two cells critical to the immune response against bacteria.
GenomeWeb Daily News has more on this paper here.
Also in Science, investigators from Harvard Medical School and Yale University publish two papers showing the promise of recoded DNA. In one report, the scientists manipulated the genetic code of a strain of Escherichia coli by replacing a rare stop codon, the UAG stop codon, for another stop codon, UAA. Since the stop codon function signaling a halt in protein production was still intact, the researchers were able to make UAG encode nonstandard amino acids giving the E. coli increased their resistance to bacteriophages. In the second paper, the investigators identified 42 genes essential for E. coli survival and removed all instances of 13 rare sense codons in each one. They found that about half of the codons thought to be essential could be replaced with no untoward effects.