Modes of Inheritance

What is penetrance in genetics

Penetrance is the likelihood that a person with a specific gene mutation will show the associated disease or trait

What is the definition of a Mendelian disorder

A disease that segregates in families according to Mendels law

What primarily causes a Mendelian disorder

A change in a single gene

What is autosomal dominant inheritance

A pattern where one mutated copy of a gene is enough to cause a disease

On which DNA base does methylation most commonly occur

Cytosine

How does methylation relate to cancer

Increased methylation can silence tumour-suppressor genes, contributing to cancer development

What is genomic imprinting

It is when gene expression differs depending on wether the gene is inherited from the mother of the father

What is imprinting controlled by?

Methylation

What type of mutations commonly affect mitochondrial DNA

Point mutations and deletion

What is mitochondrial heteroplasmy

The presence of different proportions mutant and normal mitochondria in different daughter cells

What is a single nucleotide polymorphism?

A single-base alteration in the DNA sequence

What characterises Mendelian disorders?

They typically show high penetrance and have minimal environmental contribution

What is the penetrance of any single mutation in multifactorial disease

Low penetrance

What are the three main Mendelian inheritance patterns

Autosomal dominant, Autosomal recessive and X-linked

What does the ‘common disease - common variant’ model propose

That common diseases are influenced by many common genetic variant