Understanding Rare Disease
A rare disease affects fewer than 1 in every 2,000 people in the general population. However, collectively they are not uncommon as 1 in 17 people will be affected by a rare disease across their lifetime. Over 6000 rare diseases have been identified.
What does it mean if a rare disease or condition “runs in the family”?
A rare disease or condition might be described as “running in a family” if more than one person in the family has the condition. Some rare diseases that affect multiple family members are actually caused by environmental factors such as a shared lifestyle. However some conditions are caused by gene variants (also known as genetic alterations of genetic mutations).
Our genes provide the instructions for our bodies to function. Gene variants are a bit like spelling mistakes in the instructions that make us who we are. Some spelling mistakes have a bigger impact on whether the instruction can be read by the body or not. Gene variants can be inherited (passed down from parent to child). However that can occur during embryotic development and so appear for the first time in a specific adult or child in a family.
Rare diseases can be congenital (from birth), child onset or adult onset.
How is a rare disease inherited?
Some rare diseases are caused by a change in single gene, others are polygenic (involving several genes) and some are caused by interactions between genes and the environment. An example of an environmental factor is diet.
There are different ways in which a rare disease can be inherited, depending on the gene involved. The inheritance pattern will usually have been explained to you during diagnosis. However, if this was the first time you encountered this information, you might find it tricky to recall.
You can also download factsheets with visual diagrams here:
https://www.genetics.edu.au/publications-and-resources/publications-and-resources/facts-sheets
Sources for more information
Not every rare disease has a UK patient support group to send out research bulletins. Additionally, some people like to research their rare disease and keep up to date with worldwide findings. These websites contain information that has been checked by members of the medical community and are a good place to start:
Medline
This directory of genetic conditions was previously known as Genetics Home Reference. It is easy to navigate to the information you want and very readable.
https://medlineplus.gov/genetics/condition/
Gene Reviews
A reliable source of information with articles that are very detailed because they are a comprehensive point-of-care resource for clinicians. Using the advanced search function, you can search by gene or rare disease (disorder).
What does all this mean for me?
It can be difficult to translate facts sheets and articles into information that is relevant for your life and the decisions you need to make. Our RAREnavigator team includes a team member who has completed the 3-year postgraduate degree in genetic and genomic counselling at Cardiff University. She is a member of the Association of Genetic Nurses and Counsellors and can provide post-NHS genetic counselling. For example, explaining how genes work, clarifying inheritance patterns, talking through the testing process and generally helping you to understand genetics, genomics and your own results better.
Please note: We do not order genetic tests or offer diagnoses.
Are you looking for more direct support, or want to belong to a wider rare disease community?
Our RAREhub and RAREnavigator services can help - in a way that suits you and your family.