Genomics in general practice

Misconceptions about genetics
☰ Table of contents

General practitioners (GPs) can use the information below to address common misconceptions about genetic issues during discussion with patients.

Information for patients




If your father has a genetic condition, but you look more like your mother, you will not develop it

An individual’s physical similarity to other relatives (or lack thereof) does not affect their risk of developing a condition

You can only inherit a ‘female’ cancer like breast or ovarian cancer from your mother’s side

gene variants are small deoxyribonucleic acid (DNA) sequence changes (ie additions, duplications, deletions, substitutions). These variants can have a range of effects: some may cause disease (pathogenic variant), while others do not cause disease but may modify an individual’s risk of disease (eg increase risk, provide a protective effect)." data-toggle="popover" data-trigger="hover" href="#">Gene variants in BRCA1 and BRCA2 can be passed through the paternal line (a person’s father and his relatives) and maternal line
(a person’s mother and her relatives)

If you have the gene for a particular disease, you will eventually get the disease

The presence of a pathogenetic variant does not always mean an individual will develop the condition. If the gene variants shows
variable penetrance (ie penetrance less than 100%), the risk of disease can be uncertain

A ‘one-in-four’ chance of having a child with the variant means that after you have one affected child, the next three children will be unaffected

A ‘one-in-four’ chance of having a child with the variant applies to each pregnancy (for autosomal recessive conditions)

Female carriers of X-linked conditions are never affected

This is not always the case and is influenced by X-inactivation. Carriers may have a mild phenotype and are manifesting heterozygotes. For example, female carriers of Duchenne muscular dystrophy may show mild symptoms of a cardiomyopathy; female carriers of haemophilia may have a bleeding diathesis

If you have no family history of a genetic condition, you are not at risk of developing one and neither are your children

There may be no family history for a variety of reasons. For example, reduced or incomplete penetrance, recessive conditions, small family size, and new mutations (eg de novo, sporadic)

Genetic conditions can ‘skip’ a generation

In the case of autosomal recessive and X-linked conditions, affected family members may be scattered across a generation, giving the appearance of skipping generations

Genomics in general practice




Genomics in general practice (PDF 3.1 MB)