Unmasking Hidden DNA: New Methods for Unbalanced Mixtures

Finding hidden clues in mixed DNA stains can be crucial for solving mysteries involving multiple people. Scientists have been using special markers to spot minor contributors in these messy mixtures. In a recent experiment, researchers picked 18 of these markers, called DIP-InDel, and combined them with 6 other types, DIP-STR, in two separate tests. They checked how useful these markers were by looking at 200 samples and found that 23 out of 24 were quite informative. This system can pick up tiny amounts of human DNA, as little as 0.025 nanograms, and even detect a minor contributor making up just 1% of the mix. What's more, they tested this method with cell-free DNA, like what's found in maternal blood, and found it could spot at least one paternal allele in samples from pregnancies as early as 27 weeks! This new approach could make it much easier to find hidden DNA contributors and has potential for checking on babies before they're born.