Title: Genetics Basics Lesson 3: Modes of Inheritance
Headings: 
3.1  Modes of Inheritance
3.2  Autosomal Dominant Inheritance
3.3  Autosomal Recessive Inheritance
3.3.1  Autosomal Recessive Diseases
3.4  X-Linked Dominant Inheritance
3.4.1  Oral-Facial-Digital syndrome type I
3.5  X-Linked Recessive Inheritance
3.5.1  Hypohidrotic or anhidrotic ectodermal dysplasia
3.6  Complex Inheritance
3.6.1  Cleft Lip +/- Cleft Palate

Content: These disorders are called Mendelian disorders, after the geneticist Gregor Mendel. 3.2  Autosomal Dominant Inheritance
In autosomal dominant inheritance, only one copy of a disease allele is necessary for an individual to be susceptible to expressing the phenotype. With each pregnancy, there is a one in two (50%) chance the offspring will inherit the disease allele. Unless a new mutation has occurred, all affected individuals will have at least one parent who carries the disease allele. Autosomal dominant inheritance is often called vertical inheritance because of the transmission from parent to offspring. Across a population, the proportion of affected males should be equal to the proportion of affected females. Male-to-male transmission can be observed. Examples of diseases with autosomal dominant inheritance include myotonic muscular dystrophy and Huntington disease. 3.3  Autosomal Recessive Inheritance
In autosomal recessive inheritance, two copies of a disease allele are required for an individual to be susceptible to expressing the phenotype. Typically, the parents of an affected individual are not affected but are gene carriers.