The English Spotting gene
Sometimes called the Broken gene
The English spotting gene is just a small bit of the rabbit's overall DNA and gets its name from the English (Spot) breed. Many different breeds of rabbits carry the English spotting genes. Any rabbits can inherit the English spotting genes and thus be affected.
The abbreviation "En" represents the dominant version of the gene & "en" is the recessive version. Megacolon comes in to play when a rabbit inherits two of the dominant versions of the gene (En/En). This is when a rabbit can possibly have a predisposition for Megacolon.
The English Spotting gene causes a relatively random pattern of white spots... "The number, size, and placement of spots is determined during fetal development, when color pigment-forming cells migrate from the spinal region (neural crest) to the head and down the sides of the body. Modifier genes are also believed to be involved in these spotting characteristics." - Rabbit Production. 9e. J.I. McNitt, S.D. Lukefahr, P.R. Cheeke, H.M. Patton. CABI Wallingford and Boston, (2013)
A few of the different breeds that can carry the En/En genes:
French Lop X
Netherland Dwarf X
(Photo credit K.Chan, used with permission)
"Pointed" - Himalayan makred
(Photo credit C.Schmidt-Kempisty, used with permission)
French Lop X
In the recent past some have refered to the English Spotting gene as Es (English Spot), even ARBA has done this for the "broken allele".
Research papers back as far as 1995 have used En, and not Es. Most everyone today uses Es to represent the "color steel" at the E locus and not for the Spotting gene.
The English Breed
"English Spot" in the US
"Lapin Papillon Anglais" in France
The (English) breed is defined by its phenotype (physical traits). This is the observable and expressed traits that result from the interactions between the rabbit's genes and its environment. Any rabbits can carry and inherit the English spotting genes. In the example below the English breed is used.
When two rabbits mate (depending on what combinations of the English spotting genes the parents carry) you can approximate the likelihood of an individual kit inheriting the En/En combination, using a Punnett square.
Parents % of kit inheriting En/En
Charlie (En/En) x Charlie (En/En) 100%
Broken (En/en) x Charlie (En/En) 50%
Broken (En/en) x Broken (En/en) 25%
Solid (en/en) x Broken (En/en) 0%
Solid (en/en) x Charlie (En/En) 0%
Solid (en/en) x Solid (en/en) 0%
The three outcomes from the English spotting gene:
Possible predisposition for Megacolon