Read about how genetics/genomics impacts on the role of a Specialist Dietitian
My name is Sarah Boocock and I have been qualified as a dietitian for 4 years, working in adult IMD for the last 2 years. IMD encompasses a wide range of conditions that are treated dietetically with the biggest patient group on my case-load being adults with phenylketonuria (PKU). PKU is an inherited condition affecting the activity of the enzyme phenylalanine hydroxylase. This causes an inability or reduced ability to metabolise the amino acid phenylalanine; a component of all protein containing foods. Treatment is a demanding, low protein diet: natural protein is restricted and patients are prescribed a phenylalanine-free protein substitute and specially manufactured low-protein foods. Other conditions I look after include other amino acid disorders, galactosaemia which involves a low lactose diet; urea cycle disorders and organic acidaemias requiring a protein restricted diet and an emergency regime when unwell and trimethylaminuria (fish-odour syndrome) often requiring a low choline diet. My role is varied, challenging and involves constant learning. Patients are seen in clinic but the majority of my contact with them is via telephone, email and text. Patients with PKU send regular blood tests in to check blood phenylalanine concentrations and these must be reported back to them when the results are received. Many call frequently for prescription changes, GP support or for general help and advice. I spend a lot of time listening and signposting these patients to other services. Home visits, training other health professionals about IMD and diet, attending conferences, audit, research and presenting are all other parts of my role.
Genetics has a large part to play in my profession. The majority of the disorders on my case-load are autosomal recessive (an affected person has inherited a copy of an altered gene from both of their parents) and rare. This differs from a dietitian working with those who have a genetic pre-disposition to developing a condition, for example, coronary heart disease. Here, the dietitian may advise modifying diet and lifestyle to minimise the risk of developing heart disease. However, in IMD, patients are already affected and often can only be treated with diet. Many patients, even after a medical consultation will come into a dietetic appointment with questions regarding inheritance and having a family. It is common for our patients to enquire about the risk of their unborn child having the same condition as themselves and it is important that I can give a simplified, accurate answer which is understood.
The subject of genetics has changed over the last 12-18 months as there is more awareness both as health professionals and in the public eye. Genetic services and counselling are becoming better known and patients can be given the opportunity to learn more about their genetic heritage and be screened if appropriate. There have been advances in genetic testing such as the use of blood spot cards allowing a faster diagnosis. Newborn screening has developed further and more conditions are being tested for, aiming to reduce morbidity and mortality and concurrently increasing patient numbers.
Genetics and genomics are likely to affect IMD and potentially dietetic care. There will be advances in next generation screening, where sequencing will be more effective and quicker; providing patients with faster diagnoses. As the uptake and interest in genetic counselling and screening increases, it is likely more people with IMDs will be discovered. Both of these will increase patient numbers, increasing the dietetic caseload. For many patients under my care there is no currently known reason why having a metabolic disorder will shorten lifespan. Therefore they are at risk of developing the same common conditions as everyone else, for example, cancers, hyperlipidaemia or type 2 diabetes. As the awareness of the genetic link with some of these conditions continues to rise, more patients may discover they have a predisposition to developing them. My style of advice may change and be more preventative. This may involve incorporating the PKU diet to ensure it fits in with lipid lowering for a patient predisposed to high cholesterol. For some IMDs adult patient numbers are minimal but due to increased screening and new treatment regimes, more people are surviving into adulthood. This will be new territory and we will learn more about how these IMDs affect people as they age.
I feel 5 key aspects of genetics my colleagues should be aware of are:
- Be aware of new developments in genetics and genetic screening as it is a likely area a patient may enquire about.
- Aim to have a basic understanding of genetics and inheritance as it may be you a patient looks to for a simple explanation.
- Have an understanding and experience of how to do a full genetic pedigree and its implications.
- Have an understanding of how dietary management may help alter clinical phenotype of those predisposed to a condition, such as coronary heart disease.
- Be aware of local genetic services to refer patients for genetic counselling if appropriate.