To complicate matters further, some of the spotting gene patterns can be combined to produce a horse with multiple color traits, such as the Tovero. The genetics of pinto spotting patterns are still being researched and are not fully understood. Some patterns may be polygenic, dominant, or incomplete dominants, and spoting can be so minimally expressed on an individual that the animal is mistaken for a "solid" colored horse. The sabino pattern is one of the most complex, as there has been one gene identified, SB-1, that creates one type of sabino patterning, but not all sabino-patterned horses carry it. There is a DNA test for the allele associated with the frame overo pattern, which causes the controversial lethal white syndrome, and there is a DNA test for three mutations, SW-1, SW-2, an