COI (Coefficient of Inbreeding)

See below as to how COIs are computed, we use the program Kintraks

Dog
COI at 6 Generations
COI at 10 Generations
NyaStar residents
GCH CH Rossmore Lightnin Strikes, JH, CD
"Arin"
17.96%
34.33%
GCH CH RedBranch Radiant Sunset at NyaStar
"Aoife"
0.86%
14.81%
CH NyaStar's Cross My Heart
"Kayleigh"
1.49%
14.41%
GCH NyaStar's Spark to a Flame
"Ember"
1.08%
14.26%
NyaStar's One Singular Sensation
"Eoghan"
0.98%
15.36%
CH NyaStar's Dirty Little Secret
"Karma"
0.37%
9.86%
Dogs used in our program
CKC CH Caniscaeli Pop Song for Eltin
"Poppy"
12.26%
33.39
CH Sheebhin Orla
"Kerry"
1.27%
10.13%
Red Sun's Fire Rising
"Bobby"
6.65%
23.86%
CH Carraig Colo Sceolang NA, NAJ, TDX
"Scully"
1.2%
10.03%
CKC CH Shireoak Iced Flame
"Bertie"
3.96%
23.67%
GCH Aramis Farms High Road of Killary
"Gilbey"
0.81%
13.4%
CH NyaStar's BraveHeart of RiverRun
1.49%
14.41%
Can GCHX, Am CH Shireoak Caniscaeli Windsong
8.37%
27.32%
Our Litters
Heart Litter (2010) Arin X Scully (7 pups)
1.49%
14.41%
Flame Litter (2011) Aoife X Bobby (11 pups)
1.08%
14.26%
One Singular Sensation (2012) Arin X Bertie (1 pup)
0.98%
15.36%
Secret Litter (2012) Kerry X Bobby (5 pups)
0.37%
9.86%
Talk Litter (2012) Aoife X Gilbey (10 pups)
1.35%
10.75%
Wish Litter (2013) Aoife X Eoghan (8 pups)
1.49%
14.41%
Pop Litter (2013) Poppy X Red
(6 pups)
0.93%
11.29%
Promise Litter (2014) Kayleigh X Eamon (8 pups)
0.94%
12.82%
Still Litter (2014) Meg X Bobby (6 pups)
0.68%
12.41%
Planned Breedings
     

 

Below is an exerpt from

Significant Relationships by John Armstrong

Inbreeding Coefficients

While most breeders recognize that a mating between half-sibs or cousins represents inbreeding, the majority probably have no idea which is the closer relationship. This is not helped by the non-standard definition of inbreeding in some books (e.g. Onstott's "Breeding Better Dogs").

The standard definition of inbreeding is that it is any scheme which results in the sire and the dam having common ancestors. Many breeders use the term "inbreeding" for close relatives and "linebreeding" for more distantly related individuals, but there is no fundamental difference.

The parameter used to express this common heritage is called the inbreeding coefficient and was first proposed by Sewell Wright in 1922. Designated F by Wright (but more commonly IC or COI by breeders), it can theoretically range from 0 to 100%, and indicates the probability that the two alleles for any gene are identical by descent.

The primary consequence of inbreeding is to increase homozygosity. However, the IC is not a direct measure of homozygosity because the two alleles passed down from different ancestors may be functionally the same. Furthermore, some proportion of all the genes will be the homozygous because there is only one allele. The IC serves as an indicator of what proportion of the remainder may have been made homozygous by inbreeding.

The inbreeding coefficient is a function of the number and location of the common ancestors in a pedigree. It is not a function, except indirectly, of the inbreeding of the parents. Thus, one can mate two highly inbred individuals who share little common ancestry and produce a litter with a very low IC. (Because the potential number of ancestors doubles every generation, eventually you reach a point where the number of ancestors exceeds the number of individuals alive at that time. You are, therefore, bound to find some common ancestors if you go back far enough.) Conversely, it is possible to mate two closely related dogs, both of which have low ICs, and boost the IC substantially.

The most widely used approach for calculating inbreeding coefficients is Wright's "paths" method, best illustrated by a simple example. Suppose we mate half-sibs, the common ancestor, Anson, being the father. Don is the son of Anson and Bess; Eva the daughter of Anson and Claire. Fred is one of their progeny.

COI

To simplify, we don't show the ancestors that aren't shared:

COI

Now we consider a gene for which Anson carries two different alleles, a1 and a2. There is a 50% probability of the allele Anson passed to Don being passed on to Fred. There is also a 50% probability that the same allele will be passed from Anson to Eva, and a 50% probability of it being passed from Eva to Fred, if Eva got it. When dealing with events that are contingent (this *and* that must happen), we multiply the probabilities - in this case 0.5 x 0.5 x 0.5 = 0.125 (12.5%). This final number is the probability that Fred will be homozygous for either a1 or a2 because of the common grandfather.

In general, Wright's method is to determine the path from Fred to the common ancestor, Anson, and back again on the other side of the pedigree (Fred-Don-Anson-Eva-Fred), count the number of individuals in the path, excluding Fred (there are 3, Don-Anson-Eva) and then calculate ½n, where n is that number. So, in the present case, we have (½)3 or (½ x ½ x ½) = 1/8, or 12.5%. If this were the only common ancestor, the inbreeding coefficient for Fred would be 12.5%.

Now, suppose the common ancestor was one of the grandfathers of the parents (i.e. a great-grandfather of the litter). This adds an individual on each side of the pedigree, so that we will get a path of the type Fred-X-Don-Anson-Eva-Y-Fred, and the inbreeding on Anson will be (1/2)5 or 1/32 (3.125%).

Like many other genetic calculations, the IC is based on probabilities, not certainties. An individual may be more or less highly inbred than the number computed.

If we had only a single common ancestor to deal with, life would be relatively simple. However, there are two complications to deal with. The first is that there will be more than one common ancestor. Let's consider the case of first cousins. In human populations such a pairing is prohibited in some societies but allowed in others. We have already calculated the inbreeding for a single shared grandparent. First cousins have two shared grandparents, and we simply add the inbreeding coefficient for each to get 6.25%.

The second complication is that the common ancestor may be inbred. If so, his or her inbreeding coefficient will have to be calculated. To account for this we have to multiply the inbreeding coefficient calculated for Fred by (1 + FA), where FA is the inbreeding coefficient calculated for Anson. For example, if Anson is the product of a mating of first cousins, the total inbreeding for Fred will be 0.125 x 1.0625 = 0.133 (13.3%) if there are no other shared ancestors in the pedigree.

Unfortunately, in the average pedigree, there are a large number of shared ancestors. Therefore, the total inbreeding for a dog cannot generally be calculated manually and appropriate software must be used (e.g. Kintraks). Calculating inbreeding for only the first few generations is not particularly useful. If there are more than one or two common ancestors in four or five generation pedigree, the inbreeding is probably already higher than desirable. Unfortunately, having none is no guarantee that common ancestors will not occur in abundance further back, and some pedigrees of this type still achieve moderately high inbreeding coefficients. Neither can be number of shared ancestors be used as a reliable guide, as the inbreeding coefficient is very sensitive to when and where they occur in a pedigree.