News story
28 February 2025
It’s Rare Disease Day 2025, and we are sharing a Q & A interview by Kitty Caller who carried out some work experience with us last summer.
Kitty interviewed Dr. Carmen Minea, trainee Consultant Doctor, and Miss Ruby Cross, Clinical Nurse Specialist Inherited Metabolic Disorders, from the Lysosomal Disorders Unit at Addenbrooke’s, finding out many interesting facts about rare diseases along the way.
We were intrigued to learn how rare diseases are named and whether is it possible to prevent diseases being passed on through developments in genomics. Read on to find out more…
Has ACT ever helped your department?
ACT has supported us in attending a national conference. This was highly appreciated. Participating in conferences and courses enhances our knowledge of rare diseases which then translates into better care of our patients.
What counts as a rare inherited disease?
Inherited metabolic diseases (IMD) are a group of genetic, inherited disorders of the metabolism.
A rare disease is a condition that affects less than five in 10,000 people of the general population.
How many different types of diseases do you treat?
There are over are over 500 inherited metabolic disorders. Some of those diseases are more common than others. For that reason, we only see some of these diseases in our Lysosomal Unit in Cambridge. It is not unusual to have only one patient with a particular condition.
Please can you give an example of a rare inherited disease?
Phenylketonuria, homocystinuria and maple syrup urine disease are 3 examples of inherited rare disorders which are screened for via a blood spot from a heel prick test in newborn babies.
Please can you explain the details of how these diseases are transmitted?
The majority of inherited metabolic disorders are inherited from your parents. Most frequently the parents will be healthy people with an affected copy of the gene each one. When a child inherits the two affected genes, one from each parent, they will manifest the disease. This is known as an autosomal recessive inheritance.
There are other types of inheritance where only one copy of the gene is needed from one affected parent to have the disease. This is called autosomal dominant or X-linked inheritance.
Sometimes, a mutation in the gene can happen spontaneously when the child is developing as an embryo. In this case, that child will be the first one in the family to have the disease.
Is it possible to prevent diseases being passed on through developments in genomics?
Many of our patients have the possibility to have a baby without the condition is possible using pre-implantation genetic testing. This will select the embryo which will develop into a healthy baby.
Are any inherited diseases also contagious?
No. All the diseases are passed on through genetics, not pathogens, and therefore cannot be spread from person to person.
How many people in the UK have such diseases?
There are currently around 20,000 children and adults living with an inherited metabolic disorder in the UK.
How difficult is it to diagnose people with rare inherited diseases?
As we already mentioned, some of these diseases are screened for at birth. However, for the large majority of people with these conditions the diagnosis pathway is not very easy.
Some of the diseases will manifest in the first years of life and will have typical symptoms which can be easily spotted by a specialist in rare diseases. Sometimes the picture will not be so clear, especially when the disease manifests in adulthood, and the time until diagnosis can be up to 5-7 years.
This is the case for Pompe Disease in adults, one of the rare conditions which we see here; patients with this condition are seen by many specialists before the diagnosis is made. Also, we have to keep in mind that most doctors and other medical staff are not familiar with rare diseases, and this makes the diagnosis even more difficult.
How are rare diseases identified?
The diseases that are responsible for different metabolism problems can be identified by biochemical tests. Because the diseases are caused by genetics, most patients who present symptoms are diagnosed through genomic testing.
How do they get named?
This is a very interesting question. A rare metabolic disease occurs when a defective gene results in an enzyme deficiency and, as a result, another substance will accumulate and be responsible for the disease’s manifestation. In this case the disease could be named for the substance that accumulates – an example is phenylketonuria. Sometimes a disease will be named for the missing enzyme.
We have several diseases that are named by the person who discovered them. This is the case of Pompe Disease, which was named after the pathologist Johannes C. Pompe who first described the disease in a baby.
Is having a rare inherited disease necessarily a bad thing for the patient?
For some diseases, we have effective treatment which must be maintained for life. The treatment could be a burden for some of the patients, but they can have a perfectly healthy life. This is the case for patients with Gaucher Disease.
There are some inherited rare diseases where patients must follow a strict diet during their childhood. When they become an adult, the diet can be less restrictive and they can have a normal life.
We are still trying to understand why some people can have a specific genetic mutation and biochemical alteration in their blood, but they never manifest the disease.
What do you find so interesting about working in this field?
Rare Diseases is a very special area to work where we continually learn new things about the disease and patients. The rarity of the diseases keeps professionals from all over the world working together for our patients’ benefit. It is also highly rewarding and comes with a lot of responsibility to carefully deal with complex patients.
If someone wanted to work in this field, what would they need to study?
People with different backgrounds are now working in rare diseases after finishing their normal training in an area. From doctors and nurses to people with an interest in advocating for patients affected with rare diseases, I would say that this is not an ordinary job, it is a vocation.
Visit www.act4addenbrookes.org.uk/donate to support the Rare Diseases Department at Addenbrooke’s.
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