Downunder is a dominant marking gene that adds color to the belly that may extend from the chin to the area between the hind legs. Downunder is thought to be a lethal homozygous gene, meaning an animal that inherits two copies of downunder gene (DU/DU) is never born, but is rather, resorbed in utero. Downunder, when combined with roan and the dominant white spotting gene, has shown to produce megacolon. Megacolon (MC) is a condition where the nerves that control intestinal function, do not fully form. This causes an inability to pass feces. They become bloated and malnourished. This is an incurable condition, and so it is in the rat's best interest to avoid these combinations.
Description: Downunder being a marking gene that adds color to the belly, is ideally combined with markings that would otherwise have a clean white belly. Downunder does not display visibly with Irish, english Irish, or Essex. Ideally colors would be darker as this showcases the markings more clearly. Agouti based varieties do not show the belly stripe well, due to the lighter underside.
The downunder rat will have standard markings on the topside, with a corresponding belly stripe or spots. A "mirror image." A belly stripe should to be as solid as possible. If the corresponding markings are spots, the goal should be numerous and evenly spread spots on the underside.
Vari-capped is a variety described by the AFRMA. This is a capped rat with spots running down the spine and sides like a variegated. And spotting present on the belly.
* Incomplete hood or belly stripe.
* White spots on the belly stripe.
* Uneven belly marking.
* Inadequate spotting
History: Downunder originated at Rodent Ranch Stud (Owned by club president Cindy Sautchuck) in New South Wales, Australia. The first Downunder produced, was hairless, however he died at 16 weeks due to complications with the hairless gene. A subsequent breeding of the same pair produced the first furred Downunder rat, and he was called Enigma.
The reasoning for the name "Downunder," was twofold. The name corresponds to the nature of the marking, as well as Australia being synonymous with the term Down Under.
Downunder rats were first imported to the United States by Connie Perez Of Rat Genesis, in December 2002.