Feline non-repetitive mitochondrial DNA control region database for forensic evidence

Abstract

The domestic cat is the one of the most popular pets throughout the world. A by-product of owning, interacting with, or being in a household with a cat is the transfer of shed fur to clothing or personal objects. As trace evidence, transferred cat fur is a relatively untapped resource for forensic scientists. Both phenotypic and genotypic characteristics can be obtained from cat fur, but databases for neither aspect exist. Because cats incessantly groom, cat fur may have nucleated cells, not only in the hair bulb, but also as epithelial cells on the hair shaft deposited during the grooming process, thereby generally providing material for DNA profiling. To effectively exploit cat hair as a resource, representative databases must be established. The current study evaluates 402 bp of the mtDNA control region (CR) from 1394 cats, including cats from 25 distinct worldwide populations and 26 breeds. Eighty-three percent of the cats are represented by 12 major mitotypes. An additional 8.0% are clearly derived from the major mitotypes. Unique sequences are found in 7.5% of the cats. The overall genetic diversity for this data set is 0.8813±0.0046 with a random match probability of 11.8%. This region of the cat mtDNA has discriminatory power suitable for forensic application worldwide.

Figure 1. Network diagram of universal mitotypes and subtypes for domestic cat CR

Circled letters indicate the universal mitotypes. Circles encompassing mitotypes are not to scale, although A is the most common. Subtypes are indicated at nodes. Stars indicate theoretical intermediary mitotypes predicted by network analysis. Numbers on branches indicate nucleotide position changes in the sequence alignment with the Sylvester reference sequence (SRS). Three unattributed groups (OL1–3) are indicated as well.

Figure 2. Frequency of feline universal mitotypes in random bred populations

Frequencies of all 12 universal mitochondrial haplotypes for each random bred group are present. Outlier group 1 (OL1) is not represented as it is restricted to Fancy breed cats. Unique types (U) are presented as well.