Investigation of human DNA profiles in house dust mites: Implications in forensic acarology

H. Çakan, K. Güven, F. E. Çevik, M. Demirci, S. Saribas,

Abstract: House dust mites are microscopic arthropods commonly found in many households. Since they feed on the flakes of shed human skin, human genetic material is expected to be present in these creatures. We conducted a study to find out if house dust mites can carry the DNA of the house occupants. If this were true, could human DNA isolated from the mites, obtained from a crime scene, be used as evidence in court?
Dust samples were collected from 27 dwellings using a modified vacuum cleaner. Mites have been isolated from these dust samples by a floating method. Blood samples were obtained from 40 individuals residing in these households. DNA was isolated both from the blood samples and collected mites, and then amplified to detect 9 miniSTR loci by PCR using AmpF&TR MiniFiler (Applied Biosystems) kit. PCR products were processesed in capillary electrophoresis to obtain electrophoregrams.
In this study, we detected human DNA in 10.25% of house dust mites collected from 26 out of 27 dwellings (96.3%). Total of 1740 mite samples including different mite species were obtained from the dust samples. DNA profiles of 4 individuals among 39 people (10.25%) from these 26 homes showed an exact match with those found in the mite samples from the same house. Minimum 2 miniSTR loci and maximum 8 mini-STR loci were genotyped from the collected samples in 21 out of 26 houses aforementioned.
We identified human DNA in house dust mites suggesting that one can investigate a crime by analyzing DNA samples from house dust mites found in a crime scene, and comparing them with the DNA profiles obtained from victims and suspects. Therefore, house dust mites can be used as evidence in fields of forensic sciences.
Keywords: forensic entomology, house dust mites, Dermatophagoides spp. human DNA, miniSTR analysis.