Understanding Patterns of Inheritance
Genetic disorders are diseases resulting from an abnormalgene, often described asa mutation.
That’s because an abnormal product can cause harm even if the other chromosomes codes for a normal product.
Examples of autosomal dominant disorders include Huntington’s disease and Marfan syndrome.
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Sometimes, however, these disorders result from a new mutation and happen in people with no family history.
A person with only one abnormal copy will be a carrier, but will not have the disease.
Carriers will not have any signs or symptoms of the disorder.
Carriers have a 50% chance of passing the mutation to their children.
Females have two X chromosomes and will have the disorder if either of the X chromosomes carries the mutation.
Most times, males have more severe symptoms of an X-link disorder than females.
X-Linked Recessive
In X-linked recessive disorders, the mutated gene occurs on the X chromosome.
However, a female with a genetic mutation on one X chromosome is a carrier of that disorder.
Examples of X-linked recessive disorders are hemophilia andred-green color blindness.
Each mitochondrion contains a small amount of DNA: A mutation of that DNA is responsible formitochondrial disorders.
Mitochondrial disorders are passed down from mothers to their sons or their daughters.
An example of a mitochondrial inherited disorder is Leber hereditary optic neuropathy, a form of sudden vision loss.
All sons of a man with a Y-linked disorder will inherit the condition from their father.
Codominance
Codominant inheritance involves a relationship between two versions of a gene.
Each version of a gene is called an allele.
Genetic Alliance; New York-Mid-Atlantic Consortium for Genetic and Newborn Screening Services.Appendix E: inheritance patterns.
In:Understanding genetics: a New York, Mid-Atlantic guide for patients and health professionals.
Genetic Alliance; 2009.
National Library of Medicine: MedlinePlus.What are the different ways in which a genetic condition can be inherited?.
New South Wales Health Education & Training Institute Centre for Genetics Education.Mitochondrial inheritance.
Cleveland Clinic.Leber hereditary optic neuropathy (LHON).
National Organization for Rare Disorders.Swyer syndrome.
National Human Genome Research Institute.Codominance.
