Provided herein is a DNA analysis method for DNA in an amplified, adapted library, comprising partitioning the amplified, adapted library into at least a first subsample and a second subsample; capturing a plurality of target regions comprising sequence-variable target regions from the first subsample, thereby providing captured regions; performing multiplex amplification of segments comprising recombined CDR3 sequences from the second subsample using a plurality of first primers that bind V regions and a plurality of second primers that bind J regions, thereby providing CDR3-enriched DNA; and sequencing the captured regions and the CDR3-enriched DNA.