Abetalipoproteinemia

Overview

Abetalipoproteinemia is a very rare inherited condition that affects how your body absorbs fat and certain vitamins from food. This can lead to problems with digestion, the nervous system, and the eyes. It is also called Bassen-Kornzweig syndrome.

No. Abetalipoproteinemia is extremely rare, affecting fewer than 1 in 1 million people worldwide.

The condition usually appears in infancy or early childhood. It affects boys and girls equally and can occur in any ethnic group. Symptoms often begin when a baby is a few months old.

Symptoms

Common symptoms

• Poor weight gain and slow growth in babies
• Frequent, pale, foul-smelling, greasy stools (steatorrhea)
• Unusual tiredness or weakness
• Problems with balance and walking
• Tingling or numbness in the hands and feet
• Blurred or poor vision, especially at night
• Tremors or involuntary movements
• Bowel problems such as diarrhea

Symptoms in children

• Failure to thrive (not growing or gaining weight as expected)
• Frequent fatty stools
• Delay in reaching milestones like sitting, walking, or talking
• Muscle weakness and difficulty with coordination

Symptoms in older adults

• Without treatment, older children and adults may develop progressive nerve damage, leading to poor balance and difficulty walking.
• Vision loss due to damage to the retina (the part of the eye that senses light) may become worse over time.
• Some people experience muscle wasting or weakness, especially in the arms and legs.

Causes

Main causes

• Abetalipoproteinemia is caused by changes (mutations) in the MTTP gene. This gene provides instructions for making a protein that helps package fats and cholesterol into particles that can travel in the blood.
• Without this protein, the body cannot absorb dietary fats and fat-soluble vitamins from food in the intestines, and the liver cannot release fats into the bloodstream.
• The condition is inherited in an autosomal recessive pattern. A child must receive a mutated copy of the gene from both parents to develop the condition.

Risk factors

• Having two parents who are carriers of a mutated MTTP gene (they do not have the condition themselves, but each carries one copy of the mutated gene)
• Being born to parents who are close blood relatives (such as cousins) increases the chance of inheriting rare recessive conditions

When to see a doctor

See a doctor urgently if:

• If you or your child have sudden changes in vision, difficulty walking, unexplained weakness, or severe digestive issues, seek medical help the same day.
• If you are experiencing new heart palpitations, chest pain, or passing out, call your local emergency number immediately.

Book a routine appointment if:

• If your baby is not gaining weight or has frequent, pale, greasy stools, talk to your pediatrician or family doctor.
• If you have a family history of abetalipoproteinemia, speak with a genetic counselor about your risks and whether genetic testing is appropriate.
• If you are already diagnosed, see your metabolic specialist and dietitian regularly for monitoring.

Diagnosis

Doctors suspect abetalipoproteinemia when blood tests show very low cholesterol and triglycerides, and when a blood smear shows abnormally shaped red blood cells called acanthocytes. A genetic test can confirm the diagnosis.

Tests that may be done

• Blood tests for cholesterol, triglycerides, and fat-soluble vitamin levels
• Peripheral blood smear to look for acanthocytes
• Genetic testing for MTTP gene mutations
• Liver function tests to assess liver health
• Eye exam (fundoscopy) to check for retinal changes

What to expect at your appointment

Because the condition is so rare, diagnosis may take time. Your doctor may refer you to a metabolic specialist, a geneticist, and a dietitian. You can expect to have blood tests and possibly an eye exam. The process is usually straightforward once the condition is suspected.

Treatment

There is no cure for abetalipoproteinemia, but treatment can be very effective. The main goals are to replace the fat-soluble vitamins your body cannot absorb and to modify your diet so that you get enough essential fats without overloading the digestive system. Treatment must start early and continue for life.

Self-care at home

• Take all prescribed vitamin supplements and medications exactly as directed by your healthcare provider.
• Work closely with a registered dietitian to build a meal plan that is low in long-chain fats but still contains essential fatty acids.
• Stay hydrated and avoid foods that cause diarrhea or digestive discomfort.
• Keep all regular appointments with your medical team.
• Monitor for new symptoms and report them early.

Medical treatments

Doctors prescribe high-dose supplements of fat-soluble vitamins (including vitamins A, D, E, and K) to prevent deficiencies. These are usually taken with meals. A specialized diet that limits certain types of fats, such as very long-chain fatty acids, while providing essential fats through specially designed formulas or oils, is commonly used. Physical therapy, occupational therapy, and speech therapy may also be recommended to help with motor skills and coordination.

When is surgery considered?

Surgery is not a standard treatment for abetalipoproteinemia. In some rare cases, surgery may be needed for a complication such as an intestinal blockage, but this is uncommon.

Living with this condition

Living with abetalipoproteinemia means making daily choices that support your health. You will need to stick to a low-fat diet, take vitamin supplements regularly, and see a medical team that includes a metabolic doctor, dietitian, eye specialist, and neurologist. Planning meals, carrying supplements, and scheduling appointments are part of the routine.

Lifestyle tips

• Meet regularly with a registered dietitian who understands your condition.
• Find safe, enjoyable physical activities that help with balance and strength, such as swimming, cycling, or physical therapy exercises.
• Avoid alcohol and smoking, as they can worsen nerve and liver problems.
• Wear medical identification or carry a card that explains your condition in case of emergency.
• Join a support group for rare genetic disorders to connect with others who face similar experiences.

Diet and exercise

Your diet should include small amounts of essential fats (like omega-3 and omega-6 fatty acids) to support brain and vision health, while avoiding fats that are poorly absorbed. A dietitian can help you choose healthy options. For exercise, aim for gentle, regular activity that improves coordination and muscle strength. Always check with your doctor before starting a new exercise routine.

Mental health and emotional wellbeing

Living with a rare condition can be stressful and may bring feelings of isolation or worry. It is normal to feel anxious or overwhelmed at times. Talking with a counselor or psychologist can help you cope. If you ever feel that life is not worth living, or have thoughts of harming yourself, please reach out to a mental health crisis line right away — these services are free, confidential, and available in many countries.

Prevention

Abetalipoproteinemia cannot be prevented because it is inherited. However, genetic counseling is available to help families understand their risk. Prenatal testing and preimplantation genetic diagnosis may be options for some families.

Screening programmes

Carrier testing for parents and family screening can be discussed with a genetic counselor. Some newborn screening programs may include tests that can raise suspicion of the condition, but not all regions screen for it.

Complications

If left untreated

• Progressive nerve damage leading to difficulty walking, loss of coordination, and muscle weakness
• Vision loss due to damage to the retina, which may lead to blindness
• Intellectual disability or cognitive decline in some cases
• Abnormal heart rhythm or heart failure due to vitamin E deficiency
• Osteoporosis or bone fractures from low calcium absorption
• Growth failure in children

Long-term outlook

With early diagnosis and careful treatment, the outlook is far better than it was in the past. Most people with abetalipoproteinemia who follow their treatment plan can lead productive and fulfilling lives. Research continues to improve care, and support from healthcare teams and patient communities can make a real difference.

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