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I'm Dr. Simon Holden,
a consultant in clinical genetics in
the Department of Clinical Genetics at Addenbrooke's Hospital in Cambridge.
I'm also an associate lecturer at
the University of Cambridge and this presentation is on dominant inheritance.
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This is a relatively common form of inheritance and we'll cover some of
the broader aspects as well as some of the details that students should be aware of.
At the end of this lecture,
students should understand autosomal dominant inheritance.
They should be familiar with this and how to recognise it from a family tree.
They should also be familiar with some of the more common autosomal dominant conditions.
Students should understand the importance of penetrance, and
variable expressivity and anticipation in relation
to these disorders, and have an understanding of
the importance of mosaicism and its relevance to genetic counselling.
They should be able to describe autosomal dominant inheritance
and the associated features to a patient.
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This slide shows the features of autosomal dominant inheritance.
These are caused by a mutation (or pathogenic variant) in a single autosomal gene.
An individual will be at risk if they're heterozygous for the mutation.
The trait or disorder is transmitted from generation to
generation, that is to say, it shows vertical inheritance or transmission.
Males and females are usually equally affected.
An affected parent of either sex can transmit the disorder to both sons and daughters.
An affected parent transmits the condition, on average,
to half their sons and half their daughters i.e.,
there is a one-in-two or 50 percent offspring risk.
Importantly, dominant inheritance is distinguished
from X-linked inheritance by male-to-male transmission.
