What are the modes of genetic inheritance?

Genetic conditions can be passed on from parent to offspring in a number of different 'patterns;' these are the modes of inheritance.

In autosomal dominant conditions, only one mutated copy of the gene is required for the person to be affected.

In autosomal recessive conditions, two mutated copies of the gene are required for the person to be affected. Those individuals carrying one mutated copy of the gene are carriers.

In X-linked dominant conditions, only one mutated copy of the gene (that is located on the X chromosome) is required for the person to be affected.

In X-linked recessive conditions, two mutated copies of the gene (that is located on the X chromosome) are required for the person to be affected.