Inherited Metabolic Disorders

The story of Lorraine and her son Harry

“Harry was just 6 days old when he was diagnosed with tyrosinemia type 1. 

What this condition means for Harry is that he is now on a lifelong medication to prevent any brain, liver, or kidney damage. He follows a plant-based diet, using a synthetic form of protein to ensure a normal growth and development. “It is important to me that whatever we are having for dinner as a family, Harry’s food looks exactly the same.”

Every cloud does have a silver lining and even if it is a grey day and you’ve just been given a diagnosis, that your child has a condition, it will get better, but you must allow it to get better.”
Lorraine - Harry’s mother

What are inherited metabolic disorders?

Inherited metabolic disorders (IMDs), also known as inborn errors of metabolism (IEMs) are a group of rare disorders caused by genetic defects that affect the body's ability to break down particular nutrients in food e.g. amino acids. Inherited (most often via both parents) and detected shortly after birth by newborn screening, via a blood spot test. IMDs are usually caused by defects in enzymes that help break down ('metabolize') food, which results in the production of abnormal protein, which in turn can alter the normal functioning of cells. If not effectively managed, this build-up can lead to severe long-term health issues, including irreversible brain damage.

Among the most prevalent inherited metabolic disorders are phenylketonuria (PKU), maple syrup urine disease (MSUD), and tyrosinemia (TYR). 

PKU occurs in just 1:16,000 newborns.

Tyrosinemia type 1 occurs in just 1:100,000 newborns.

MSUD occurs in just 1:185,000 newborns.

HCU occurs in just 1:344,000 newborns.

The role of nutrition in inherited metabolic disorders

For around fifty of the known inherited metabolic disorders, management is through a lifelong commitment to a restricted diet. In the example of the amino acid disorder Phenylketonuria (PKU), individuals cannot break down the amino acid phenylalanine, which leads to a build-up on the brain. A build-up of this kind can cause long-term health issues, including irreversible brain damage. 

Since amino acids such as phenylalanine are the building blocks of the protein we eat, PKU patients must stick to a low-protein diet, alongside supplementation of the essential and non-essential amino acids that our bodies need to function properly. For all people with metabolic disorders managed through diet, special foods will help them to meet their nutrition requirements while providing the necessary dietary management of the disorder.


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