Inheritance and genetics

Many muscle-wasting conditions have a genetic cause, which means that they can be passed down generations (inherited). However not all are inherited in the same way. It’s important to have an understanding of what condition you or your family has.

We’d recommend reading these pages together with our pages relating to your muscle-wasting condition.

This factsheet provides a brief summary of genetics and typical inheritance patterns.

Understanding these patterns within a family tells us about the likelihood of another family member being affected or not.

This information is particularly important in family planning. If you have any concerns or questions about inheritance and genetic testing, do discuss these with your GP who can refer you to your local genetics counsellor.

DNA, chromosomes and genes

Deoxyribonucleic acid (DNA) contains instructions for the functioning of living organisms. Inside our cells, DNA is organised into structures called chromosomes. These are found in the cell nucleus.

Imagine your DNA as a recipe book, and your genes as the recipes. Our cells use these [genetic] recipes to make proteins, which are essential for a wide range of biological processes in the body.

Almost all of our cells contain 23 pairs of chromosomes (46 in total). These include one pair of sex chromosomes (XX for females, XY for males) and 22 pairs of non-sex chromosomes (autosomes).

For each pair of chromosomes, we inherit one from our mother and one from our father. The rest come from one parent or the other.

For example, some genes involved in energy production are inherited from the mother only. These genes are known to be associated with mitochondrial diseases.

What is a genetic mutation?

A genetic mutation is a change in the DNA code. This can happen by complete chance, for example if the cell makes a ‘mistake’ during DNA replication.

Sometimes this happens as a result of environmental factors, such as smoking, excessive exposure to sunlight or exposure to radiation.

Our cells have natural mechanisms for recognising mutations and correcting them, but these are not always 100 percent effective.

Depending on where a mutation occurs, and the type of mutation it is, the effect could be harmless. Or it could ‘disrupt’ a gene and result in a genetic condition such as muscular dystrophy.

How are muscle-wasting conditions inherited?

Muscle-wasting conditions have different inheritance patterns, depending on the type of condition and which gene is mutated.

Where can I get advice?

There are a number of specialist genetic centres throughout the country that do genetic tests and offer advice. Your GP can arrange a referral to a clinical geneticist or genetic counsellor at your local genetics centre.