Metabolic disorders refer to illnesses that develop when the body cannot properly process fats, proteins, sugars or nucleic acids. Inherited metabolic disorders refer to different types of medical conditions caused by genetic defects — most commonly inherited from both parents — that interfere with the body’s metabolism. The prognosis and treatments for different metabolic disorders vary.
Inherited metabolic disorders are one cause of metabolic disorders, and occur during a defective gene induces an enzyme deficiency. These diseases, or whatever there are many subtypes, are known as inborn errors of metabolism. Metabolic diseases can further occur when the liver or pancreas do not function correctly.
Types of Inherited Metabolic Disorders
Centuries of inherited metabolic disorders have remained identified. Some of the more common and important genetic metabolic disorders include:
Lysosomal storage disorders: Lysosomes are spaces inside cells that break down waste products of metabolism. Several enzyme deficiencies inside lysosomes can result in the buildup of toxic substances, causing metabolic disorders including:
Niemann-Pick disease (babies develop liver enlargement, difficulty feeding, and nerve damage)
Hurler syndrome (abnormal bone structure and developmental delay)
Gaucher disease (bone pain, enlarged liver, and low platelet counts, often mild, in children or adults)
Krabbe disease (progressive nerve damage, developmental delay in young children; occasionally adults are affected)
Tay-Sachs disease (progressive weakness in a months-old child, progressing to severe nerve damage; the child usually lives only until age 4 or 5)
Fabry disease (pain in the extremities in childhood, with kidney and heart disease and strokes in adulthood; only males are affected)
Maple syrup urine disease: Deficiency of an enzyme called BCKD causes the buildup of amino acids in the body. Nerve damage results and the urine smells like syrup.
Galactosemia: Impaired breakdown of the sugar galactose leads to jaundice, vomiting, and liver enlargement after breast or formula feeding by a newborn.
Phenylketonuria (PKU): Deficiency of the enzyme PAH results in high levels of phenylalanine in the blood. Mental retardation results if the condition is not recognized.
Mitochondrial disorders: Problems inside mitochondria, the powerhouses of cells, lead to muscle damage.
Glycogen storage diseases: Problems with sugar storage lead to low blood sugar levels, muscle pain, and weakness.
Friedreich ataxia: Problems related to a protein called frataxin cause nerve damage and often heart problems. Inability to walk usually results in young adulthood.
Peroxisomal disorders: Similar to lysosomes, peroxisomes are tiny spaces filled with enzymes inside cells. Poor enzyme function inside peroxisomes can lead to the buildup of toxic products of metabolism. Peroxisomal disorders include:
Zellweger syndrome (abnormal facial features, enlarged liver, and nerve damage in infants)
Adrenoleukodystrophy (symptoms of nerve damage can develop in childhood or early adulthood depending on the form.)
Metal metabolism disorders: Levels of trace metals in the blood are controlled by special proteins. Inherited metabolic disorders can result in protein malfunction and toxic accumulation of metal in the body:
Hemochromatosis (the intestines absorb excessive iron, which builds up in the liver, pancreas, joints, and heart, causing damage)
Wilson disease (toxic copper levels accumulate in the liver, brain, and other organs)
Organic acidemias: methylmalonic acidaemia and propionic acidemia.
Urea cycle disorders: ornithine transcarbamylase deficiency and citrullinemia
Symptoms of Inherited Metabolic Disorders
The symptoms of metabolic disorders vary depending on the individual condition.
- Abdominal pain
- Vomiting
- Lethargy
- Poor appetite
- Weight loss
- Jaundice
- Seizures
- Coma
- Failure to gain weight or grow
- Developmental delay
- An abnormal odour of urine, breath, sweat, or saliva
There are four categories of symptoms: acute symptoms, late-onset acute symptoms, progressive general symptoms and permanent symptoms.
Inherited Metabolic Disorders Diagnosis
Metabolic disorders can be started at birth, and many can be distinguished by routine screening. If a metabolic dysfunction is not known early, then it will be diagnosed later in life, if symptoms appear. Specific blood and DNA tests can be performed to diagnose genetic metabolic disorders. Metabolic disorder screening in newborns the following methods-
- Blood test
- Hearing test
- Skin test
Treatment of Inherited Metabolic Disorders
Metabolic disorders can be treatable by nutrition management, especially if detected early. Treatments for genetic metabolic disorders follow a few general principles:
- Decrease or eliminate consumption of any food or medicine that can’t be metabolized properly.
- Replace the enzyme or chemicals that are missing or inactive.
- Eliminate toxic products of metabolism that accumulate due to the metabolic disorder.
Treatment may include such measures as:
- Special diets that exclude specific nutrients
- Taking enzyme replacements
- Treating the blood among chemicals to detoxify dangerous metabolic by-products
