There are more male orange cats than females because this gene is located on the X-chromosome, which males only have one copy of. He and his research team analyzed DNA in skin tissue from cats with and without orange fur, and found a mutation to the ARHGAP36 gene. In orange cats, the missing segment is located on an intron, or noncoding region, of the ARHGAP36 gene, which is also in neuroendocrine tissues (especially the hypothalamus), adrenal glands, and pituitary glands. To be orange, a female cat must have the orange gene on both X chromosomes, so no matter which one is deleted, the orange gene still dominates. Sasaki believes that when a mutated ARHGAP36 is expressed as orange fur in cats, the missing part of the gene would have suppressed orange coloration had it been present.