There are traits manifested in certain eukaryotes that result from extranuclear inheritance. The mitochondria, for instance, contain genetic material independent of the chromosomes inside the nucleus.
During the union of gametes, the mitochondrial DNA from the maternal parent is imparted to its offspring. Hence, when the mitochondrial DNA is expressed the resulting traits would be extranuclear in nature, and determined largely as maternal effect. Inherited diseases relating to mitochondria is called mitochondrial disease.
Results from our forum
... genome is approximately 16kb pairs. The real meat of mitochondrial inheritance is that cytoplasmic genes do not demonstrate Mendelian patterns ... That is a whole other topic though. On an interesting note, extranuclear inheritance is not thwarted by substituting a genetically different ...
See entire post