Why do white mice exist? - briefly
White laboratory mice are bred for genetic uniformity, which simplifies experimental control and data interpretation. Their lack of pigment also facilitates visual observation of physiological processes.
Why do white mice exist? - in detail
White mice result from a genetic mutation that disables melanin production. The mutation affects the tyrosinase enzyme, preventing the synthesis of pigment in skin, fur, and eyes. Animals carrying two copies of the recessive allele display a completely white coat and pink‑eyed appearance, a condition known as albinism.
Selective breeding has amplified this phenotype in laboratory colonies. Breeders maintain homozygous albino lines because they:
- provide a uniform visual background for surgical and imaging procedures;
- simplify the identification of genetic modifications when using coat‑color markers;
- reduce variability in behavioral studies where pigmentation could influence light perception.
Commercial suppliers propagate these strains through controlled mating programs, ensuring genetic stability and disease‑free status. The use of white mice also facilitates the application of transgenic technologies. Fluorescent reporters and bioluminescent assays become more detectable against a light‑colored fur, improving signal‑to‑noise ratios.
Ecologically, albino individuals occur sporadically in wild populations, but predation and reduced camouflage limit their survival. In captivity, the absence of natural selective pressures allows the phenotype to persist and become a standard model organism.