Long-Chain 3-Hydroxy Acyl-CoA Dehydrogenase Deficiency (LCHAD)
What is Long-Chain 3-Hydroxy Acyl-CoA Dehydrogenase Deficiency (LCHAD)?
Long-chain 3-hydroxy acyl-CoA dehydrogenase deficiency, or LCHAD, is a rare genetic condition. It affects how your body breaks down certain fats for energy. Your cells contain tiny structures called mitochondria that work like power plants. When you go without food or face physical stress, these mitochondria normally burn long-chain fatty acids to make energy.
In people with LCHAD deficiency, an enzyme needed for this fat-burning process does not work properly. The enzyme is called long-chain 3-hydroxy acyl-CoA dehydrogenase. Without it, your body cannot turn certain fats into fuel. This leads to dangerously low blood sugar, especially during fasting or illness. The condition also prevents your body from making ketones, which are backup fuel molecules your brain needs when glucose runs low.
LCHAD deficiency is inherited in an autosomal recessive pattern. This means both parents must pass down a changed gene for a child to develop the condition. Most cases are detected through newborn screening programs. Early diagnosis and careful management help people with LCHAD live healthy, active lives. Treatment focuses on avoiding fasting, eating the right foods, and preventing metabolic crises.
Symptoms
- Episodes of extremely low blood sugar, especially when fasting or sick
- Extreme tiredness or lethargy that seems unusual
- Vomiting or poor appetite during illness
- Weak muscle tone or muscle pain and breakdown
- Enlarged liver that a doctor can feel during examination
- Heart problems including irregular heartbeat or weakened heart muscle
- Vision problems or damage to the retina
- Developmental delays in infants and young children
- Breathing difficulties during metabolic stress
- Seizures or loss of consciousness in severe cases
Many infants with LCHAD deficiency appear healthy at birth. Symptoms often first appear during periods of fasting, illness, or increased energy demands. Some children experience their first crisis after sleeping through the night without feeding. Quick recognition of symptoms can prevent life-threatening complications.
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Causes and risk factors
LCHAD deficiency is caused by changes in the HADHA gene. This gene provides instructions for making part of an enzyme complex needed to break down long-chain fatty acids. When both copies of the gene contain mutations, the enzyme cannot work properly. Parents who each carry one changed gene usually have no symptoms themselves. When both parents are carriers, each child has a 25 percent chance of inheriting LCHAD deficiency.
Risk factors include having parents from populations where carrier rates are higher, such as certain European and Middle Eastern communities. Consanguinity, or having parents who are blood relatives, increases risk. Family history of unexplained infant death, liver problems, or metabolic crises may suggest carrier status. Genetic counseling can help families understand their risk and make informed decisions about testing and family planning.
How it's diagnosed
Most cases of LCHAD deficiency are identified through newborn screening programs. A small blood sample taken from the baby's heel can reveal abnormal fatty acid patterns. If screening suggests LCHAD deficiency, doctors order confirmatory tests including genetic testing and enzyme activity measurements. Blood tests during a metabolic crisis show low blood sugar with inappropriately low or absent ketones. This pattern of hypoketotic hypoglycemia is a key diagnostic finding.
Urine ketone testing helps monitor metabolic status in people with LCHAD deficiency. During fasting or illness, most people produce ketones as an alternative fuel source. People with LCHAD deficiency cannot make adequate ketones, so urine ketone levels remain low even when blood sugar drops. Rite Aid offers testing through Quest Diagnostics at over 2,000 locations nationwide. Regular monitoring helps catch problems early and guide treatment decisions. Talk to your doctor about which tests are right for your situation.
Treatment options
- Avoid fasting by eating frequent meals and snacks throughout the day
- Follow a special diet low in long-chain fats and higher in medium-chain triglycerides
- Use cornstarch at bedtime to provide slow-release glucose during sleep
- Supplement with carnitine to help remove toxic fat breakdown products
- Take DHA supplements to support eye and brain health
- Monitor blood sugar regularly, especially during illness or increased activity
- Seek immediate medical care during vomiting, poor appetite, or signs of low blood sugar
- Receive intravenous glucose during illness to prevent metabolic crisis
- Work with a metabolic specialist and dietitian experienced in fatty acid disorders
- Carry emergency protocols and medical alert identification at all times
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Frequently asked questions
LCHAD deficiency is a rare genetic condition affecting how your body breaks down certain fats for energy. An enzyme needed to process long-chain fatty acids does not work properly. This causes dangerously low blood sugar and prevents your body from making ketones during fasting or illness. Early diagnosis and treatment help people with LCHAD live healthy lives.
LCHAD deficiency affects approximately 1 in 50,000 to 1 in 100,000 newborns. Carrier rates are higher in certain populations, particularly those of European descent. The condition is inherited when both parents carry a gene mutation. Newborn screening programs in most states detect LCHAD deficiency before symptoms appear.
Many babies appear healthy at birth and show first symptoms during periods of fasting or illness. Early signs include extreme tiredness, poor feeding, vomiting, or low blood sugar episodes. Some babies experience their first crisis after sleeping through the night without feeding. Newborn screening usually detects the condition before symptoms develop.
Most cases are found through newborn screening using a heel prick blood test. Screening reveals abnormal fatty acid patterns that suggest enzyme problems. Doctors confirm diagnosis with genetic testing and enzyme activity measurements. Blood and urine tests during episodes show low blood sugar with low or absent ketones.
There is no cure for LCHAD deficiency, but effective management strategies exist. Treatment focuses on preventing metabolic crises through diet and avoiding fasting. People with LCHAD can live active, healthy lives with proper care. Research continues into new therapies and better management approaches.
People with LCHAD need a diet low in long-chain fats and higher in medium-chain triglycerides. Frequent meals and snacks prevent fasting and keep blood sugar stable. Cornstarch at bedtime provides slow-release glucose overnight. A metabolic dietitian creates individualized meal plans based on age, weight, and activity level.
Ketones are backup fuel molecules your brain uses when blood sugar is low. Most people make ketones during fasting by breaking down fat. People with LCHAD deficiency cannot make adequate ketones, leaving them without backup fuel. Low ketones with low blood sugar, called hypoketotic hypoglycemia, signals a metabolic crisis requiring immediate treatment.
Metabolic crises occur when the body needs extra energy but cannot burn fat properly. Common triggers include fasting, illness with vomiting or poor appetite, surgery, and increased physical activity. Even common childhood illnesses like stomach flu can trigger crises. Preventing fasting and seeking early medical care during illness helps avoid emergencies.
Most severe cases are identified in infancy through newborn screening or metabolic crises. Some people with milder forms may go undiagnosed longer. Adults with unexplained muscle pain, exercise intolerance, or low blood sugar episodes should discuss metabolic testing with their doctor. Genetic testing can confirm or rule out LCHAD deficiency.
With early diagnosis and careful management, many people with LCHAD deficiency lead healthy, active lives. Regular monitoring, dietary management, and avoiding fasting prevent most complications. Some individuals develop vision problems or heart issues over time. Working closely with a metabolic specialist and following treatment plans improves long-term outcomes significantly.