Title: Monogenic Disorders (Single Abnormal Gene) — University of Leicester
Headings: Monogenic Disorders (Single Abnormal Gene)
Monogenic Disorders (Single Abnormal Gene)
Autosomal Dominant Inheritance
Autosomal Recessive Inheritance
X-Linked Recessive Inheritance
X-Linked Dominant Inheritance
Mitochondrial Inheritance
Imprinted Genes

Content: However, the pattern of inheritance is not always predictable because there is some chance element involved in just how much cytoplasm is passed on, and therefore just how much mitochondrial DNA is passed on is also not predictable. Mitochondrial DNA is passed on solely via the egg, as the sperm nucleus is the only part involved in fertilization, and this does not contain any cytoplasm. The pattern with mitochondrial inheritance is therefore only via transmission through an affected female to a variable number of male and female offspring, but there is no transmission from an affected male. An example of a condition that is caused by mitochondrial inheritance is Leber's hereditary optic neuropathy (LHON). LHON causes a painless loss of central vision between 12 and 30 years of age. Both eyes are affected at the same time. Males will not pass the gene to any of their children, but females with the mutation will pass it to all of their children, regardless of whether they are sons or daughters. Imprinted Genes
In most cases it does not matter if the defective copy of a gene is inherited from the mother or the father - the effect remains the same. However, there are some genes and chromosome regions where there will be a different effect depending on which parent carries the mutated copy of the gene. One example of this is on Chromosome 15.