Concurrent copy number variations on chromosome 8 and 22 combined with mutation at FGA locus revealed in a parentage testing case

Copy number variations (CNVs) are one of the major sources of human genetic diversity and are associated with rare genomic disorders as well as complex traits and diseases. A copy number variation was observed at the D8S1179 locus during routine STR based parentage testing, in which the child exhibited three alleles, “13, 15, 16”, with the putative father a homozygous “15” and the mother homozygous “13”. In addition, in the same testing case, there was a one-step mutation at the STR locus FGA, in which the putative father was a “22, 24”, the mother was a “22, 25”, and the child was a “22, 23”. After further investigations by re-amplified with different primer sets, clone-based sequencing, karyotype analysis and whole-genome SNP analysis, the results showed that the child had the CNVs at chromosome 8q24.3 and 22q11.21. In conclusion, for parentage testing cases encountered with tri-allele patterns, more testings, such as cloning sequencing, karyotyping, or even whole genome analysis, as well as more appropriate statistical estimations might be conducted to further confirm or exclude the relationship.