Visual communication aid: Autosomal recessive inheritance

There are two communication aids available to view and download (.pdf):

• Autosomal recessive inheritance: one affected parent
• Autosomal recessive inheritance: two carrier parents

Double-sided printing in colour is recommended (but not required). All content is also included below in an accessible format.

More information about these and other VCAs is available in this article.

We all have over 20,000 genes, which provide instructions for how our body works.​

Our genes are packaged into structures called chromosomes.​

We all have two copies of each of our autosomal genes, one inherited from each of our parents.​

Individuals affected by an autosomal recessive condition have a change on both copies of the gene.​

When someone has a change on just one of the two copies of the gene, they are known as being a ‘carrier’ and would not usually be expected to develop the condition.​

When someone who is affected by an autosomal recessive condition has a child, they will always pass a copy of the gene change to their child. If their partner is not affected and not a carrier, they will not pass a gene change to the child, as they do not have one.

This means all their children will be carriers, but usually would not be expected to develop the condition (figure 1).

Figure 1: Autosomal recessive inheritance when one parent is affected with the condition

When two carriers have a child together, each parent will either pass on their gene copy with the change or the copy without the change on to their child (figure 2). This means:​

• There is a 25% (1 in 4) chance of having a child affected with the condition. ​
• There is a 50% (2 in 4) chance of having a child who is a carrier of the condition (like both parents). ​
• There is a 25% (1 in 4) chance of having a child who is not affected with the condition and is not a carrier.

An unaffected child will have about a 66% (2 in 3) chance of being a carrier.

Figure 2: Autosomal recessive inheritance when both parents are carriers of the condition

• Chromosomes: Packages of DNA which are found in our cells​.
• Autosomal genes: ​These genes are located on chromosomes that are not sex chromosomes.​
• First-degree relative:​ These are your parents, full siblings and children.
• Gene change:​ Changes in a gene or chromosome used to be referred to as ‘mutations’. Now, they are more commonly called changes, alterations or variants.​

For patients

• NHS England Genomics Education Programme: Autosomal dominant inheritance animation