Title: How Genetic Disorders Are Inherited
Headings: How Genetic Disorders Are Inherited
How Genetic Disorders Are Inherited
Understanding Patterns of Inheritance
Patterns of Inheritance
Autosomal Dominant
Autosomal Recessive
X-Linked Dominant
X-Linked Recessive
Mitochondrial
Other Inheritance Patterns
Y-Linked Disorders
Codominance

Content: Genetic Testing for Huntington's Disease
Autosomal Recessive
In autosomal recessive disorders, both copies of a mutated gene—one from each parent—are present. A person with only one copy will be a carrier. Carriers will not have any signs or symptoms of the disorder. They can, however, pass the mutation to their children. If families in which both parents carry the mutation for an autosomal recessive disorder, the odds of the children having the disorder are as follows: 5 ﻿
25% risk of inheriting both mutations and having the disorder
50% risk of inheriting only one copy and becoming a carrier
25% risk of not inheriting the mutation at all
Examples of autosomal recessive disorders include cystic fibrosis, sickle cell disease, Tay-Sachs disease, and phenylketonuria (PKU). Living With Sickle Cell Disease
X-Linked Dominant
X-linked dominant disorders are caused by mutations in genes on the X (female) chromosome. In females, who have two X chromosomes, it takes a mutation in only one of the two copies of the gene for a disorder to manifest. In males (who have one X chromosome and one Y chromosome), a mutation in only one copy of the gene in each cell is enough to cause the disorder. Most times, males have more severe symptoms of an X-link disorder than females.