The development of molecular biological techniques has allowed to know the root of many genetic diseases , including diseases conditioned deletions and duplications of DNA genomic fragments - CNV ( Copy Number called Variants ) , representing approximately 5.5% of the previously described changes in the genome of pathogenic . One of the methods of examination of deletions and duplications of fragments of the genome is the MLPA ( Multiplex Ligation - called dependent Probe Amplification ) , first described in 2002.