Mendelian Inheritance patterns

Follows a predictable pattern of inheritance in humans and some species

1. Autosomal Dominant
2. Autosomal Recessive
3. X-linked Recessive
4. X-linked dominant
5. Mitochondrial

Rule of thumb:

1. Disease in every generation = Dominant
2. Disease skips generations = Recessive
3. If Male->Male transmission = Autosomal disease
4. If No male->male transmission = X-linked

• Beware of mitochondrial inheritance!

Autosomal recessive conditions are 'metabolic' - exceptions: inherited ataxias

Autosomal dominant conditions are 'structural' - exceptions: Gilbert's, hyperlipidaemia type II

1) Autosomal dominant inheritance

• generally ‘ structural-type’ disorders

exceptions: ataxia telangiectasia and Friedrich ataxia

mutation of one copy (allele) on autosome

ALL offspring of an affected person have a 50% chance of inheriting the mutation