Acronyms - Mode of Inheritance

AD - Autosomal Dominant 

One mutated copy of the mutant gene, inherited either from the mother or father is sufficient for an individual to be affected by an autosomal dominant disorder. In some cases, an affected person inherits the condition from an affected parent.

ADIP - Autosomal Dominance, Incomplete Penetrance

One mutated copy of the mutant gene, inherited either from the mother or father is sufficient for an individual to be affected by an autosomal dominant disorder. In some cases, an affected person inherits the condition from an affected parent. However, in some cases, it is known that the disease does not manifest in a certain population of genetically affected dogs. It is also sometimes observed that dogs that appear to have the same disease do not test as genetically affected. Often, the reasons are not fully known to researchers. Sometimes, it is suspected that there is a different, as yet unknown mutation, or other environmental factors that impact if or how a disease develops.

Allele

An allele is one of two, or more, versions of the same variant at the same place on a chromosome. E.g. brown coat colour vs. black coat colour

AR - Autosomal Recessive

For an individual, they have the potential to inherit from their parents either two copies of the normal gene variant, one copy of the normal and one mutation variant, or two mutation variants. Where two mutation genes are inherited, clinical signs of the disease normally occur at some point in the individual’s lifetime.

ARIP - Autosomal Recessive, Incomplete Penetrance

For an individual, they have the potential to inherit from their parents either two copies of the normal gene variant, one copy of the normal and one mutation variant, or two mutation variants. Where two mutation genes are inherited, clinical signs of the disease occur at some point in the individual’s lifetime. However, in some cases, it is known that the disease does not manifest in a certain population of genetically affected dogs. It is also sometimes observed that dogs that appear to have the same disease do not test as genetically affected. Often, the reasons are not fully known to researchers. Sometimes, it is suspected that there is a different, as yet unknown mutation, or other environmental factors that impact if or how a disease develops.

CD - Codominant

In codominant inheritance, two different versions (alleles) of a gene are expressed, and each version makes a slightly different protein. Both alleles influence the genetic trait or determine the characteristics of the genetic condition.

Diagnostic Tool

For the HGTD purposes, this refers to a gene-based test (DNA test) that is primarily designed to aid in diagnosis and/or monitoring of a particular disease. This often, but not always, looks for specific genes or markers that indicate the presence or absence of a conditions or disease (ex. Cancers) but is not normally used for breeding purposes. Indeed, it can be used where a condition or disease is not considered or known to be inherited.

....IP - ..., Incomplete Penetrance

The phrase "incomplete penetrance" can be added to types of inheritance to describe the phenomenon where a trait/disease does not manifest in a certain population of genetically affected dogs. It is also sometimes observed that dogs that appear to have the same disease do not test as genetically affected. Often, the reasons are not fully known to researchers. Sometimes, it is suspected that there is a different, as yet unknown mutation, or other environmental factors that impact if or how a disease develops.

M - Mitochondrial 

Mitochondrial inheritance, also known as maternal inheritance, applies to genes in mitochondrial DNA. Mitochondria, which are structures in each cell that convert molecules into energy, each contain a small amount of DNA. Because only egg cells contribute mitochondria to the developing embryo, only females can pass on mitochondrial mutations to their children. Conditions resulting from mutations in mitochondrial DNA can appear in every generation of a family and can affect both males and females, but fathers do not pass these disorders to their daughters or sons.

Recessive, Maternal Inheritance

The risk variants are inherited in a recessive pattern, and the disease is only expressed when both dam and offspring are deletion homozygotes. The maternal inheritance effect can sometimes be due to a physiological effect, as in the example of recessive RBP4 (microphthalmia...) where "the maternal penetrance effect arises from an impairment in the sequential transfer of retinol across the placenta, via RBP encoded by maternal and fetal genomes" (Kaukonen et. al, 2018). This is not the same as X-linked. 

RV - Risk Variant

Testing for a risk variant means that the DNA test is not absolutely determining the gene(s) responsible for a disease, but instead, the presence or absence of the genes associated with an increase or decrease in risk of developing a disease are tested for. For risk variants, it is important to know what the research has indicated the levels of risks are, before making breeding or health decisions. For example, a test that can only determine a risk of 10% would normally be treated differently than a test that determines 50% or more risk.

Variant

Refers to a specific region of the genome which differs between two genomes.

XD - X-linked Dominant

X-linked dominant disorders are caused by mutations in genes on the X chromosome, one of the two sex chromosomes. In females (who have two X chromosomes), a mutation in one of the two copies of the gene is sufficient to cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of the gene causes the disorder. In most cases, males experience more severe symptoms of the disorder than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons (no male-to-male transmission).

XR - X-linked Recessive

X-linked recessive disorders are also caused by mutations in genes on the X chromosome. In males (who have only one X chromosome), one altered copy of the gene is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons (no male-to-male transmission).

YL - Y-linked  

A condition is considered Y-linked if the mutated gene that causes the disorder is located on the Y chromosome. Because only males have a Y chromosome, in Y-linked inheritance, a mutation can only be passed from father to son.