PFIC Type 3 (MDR3 Deficiency)
What is PFIC Type 3 (MDR3 Deficiency)?
PFIC Type 3, also called MDR3 deficiency, is a rare genetic liver condition. It affects how your liver moves fats called phospholipids into bile. Bile is a fluid your liver makes to help digest fats and remove waste from your body.
When the MDR3 protein does not work properly, bile becomes toxic to liver cells. This causes cholestasis, which means bile flow slows down or stops. Over time, this damage can lead to scarring of the liver, called cirrhosis. PFIC Type 3 usually appears in childhood but can show up in adults too.
Unlike other types of PFIC, Type 3 tends to progress more slowly. Some people develop symptoms in infancy, while others may not have problems until their teenage years or later. Early detection through blood testing helps protect your liver from serious damage.
Symptoms
- Jaundice, which is yellowing of the skin and eyes
- Intense itching that gets worse at night
- Dark urine that looks like tea or cola
- Pale or clay-colored stools
- Enlarged liver or spleen
- Poor growth in children
- Fatigue and weakness
- Abdominal pain or discomfort
- Easy bruising or bleeding
- Vitamin deficiencies affecting bones and vision
Some people have mild symptoms that come and go for years. Others may not notice problems until liver damage becomes more serious. Children may simply seem tired or have trouble gaining weight without obvious liver symptoms.
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Causes and risk factors
PFIC Type 3 is caused by mutations in the ABCB4 gene. This gene tells your body how to make the MDR3 protein, which moves phospholipids into bile. When this protein does not work, bile becomes harsh and damages liver cells. You inherit this condition from your parents. If both parents carry one copy of the mutated gene, their child has a 25% chance of developing PFIC Type 3.
Risk factors include family history of liver disease, parents who are carriers of ABCB4 mutations, and certain ethnic backgrounds where the gene mutation is more common. Some people with only one gene copy can develop milder liver problems later in life. Pregnancy can trigger symptoms in women who carry the mutation, causing a condition called intrahepatic cholestasis of pregnancy.
How it's diagnosed
Doctors diagnose PFIC Type 3 using blood tests, imaging, and genetic testing. Blood tests check liver enzymes, bilirubin levels, and bile acids. Urine bilirubin testing can reveal cholestatic liver disease, showing that bile flow is blocked. Rite Aid offers testing that includes urine bilirubin, which can help identify liver problems that need further investigation.
Additional tests may include ultrasound or MRI to look at your liver and bile ducts. A liver biopsy can show the type of damage and help rule out other conditions. Genetic testing confirms the ABCB4 gene mutation and provides a definitive diagnosis. Early testing is important because treatment works best when started before severe scarring develops.
Treatment options
- Ursodeoxycholic acid, a medication that improves bile flow and protects liver cells
- Medications to reduce itching, such as antihistamines or rifampin
- Fat-soluble vitamin supplements including A, D, E, and K
- Medium-chain triglyceride oil to help with fat absorption
- Low-fat diet modifications to reduce digestive symptoms
- Regular monitoring of liver function through blood tests
- Avoiding alcohol and medications that can harm the liver
- Liver transplant for advanced cirrhosis or liver failure
Concerned about PFIC Type 3 (MDR3 Deficiency)? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
PFIC Type 3 is caused by a different gene mutation than Types 1 and 2. It usually appears later in childhood or even adulthood, while Types 1 and 2 often show up in infancy. PFIC Type 3 tends to progress more slowly and may respond better to medication. People with Type 3 typically have higher levels of a liver enzyme called GGT, which helps doctors tell the types apart.
Adults can develop symptoms of PFIC Type 3, even if they had no problems as children. Some people do not show signs until their 20s, 30s, or later. Women may first notice symptoms during pregnancy when hormone changes stress the liver. Adult onset cases may be milder but still need treatment to prevent cirrhosis.
When bile flow is blocked, bilirubin builds up in your blood and spills into your urine. This makes your urine dark and tests positive for bilirubin. A positive urine bilirubin test indicates cholestatic liver disease, which includes conditions like PFIC Type 3. This simple test helps doctors know when to do more specific liver testing and genetic analysis.
PFIC Type 3 is a genetic condition that cannot be cured, but it can be managed with treatment. Many people do well on ursodeoxycholic acid medication for years or decades. This drug helps protect your liver and slow disease progression. The only cure is a liver transplant, which is reserved for people with severe cirrhosis or liver failure.
Without treatment, PFIC Type 3 causes ongoing liver damage that leads to cirrhosis and liver failure. Cirrhosis is permanent scarring that prevents your liver from working properly. You may develop complications like portal hypertension, fluid buildup, and increased cancer risk. Early treatment with medication can prevent or delay these serious outcomes.
A low-fat diet can reduce digestive symptoms because your liver struggles to process fats properly. Medium-chain triglyceride oil is easier to absorb and can help you get needed calories. You will also need fat-soluble vitamin supplements since your body cannot absorb these vitamins from food. Work with a dietitian who understands liver disease to create a meal plan that supports your health.
Most doctors recommend blood tests every 3 to 6 months to monitor liver function. These tests check liver enzymes, bilirubin, bile acids, and clotting factors. More frequent testing may be needed if your symptoms change or your medication dose is adjusted. Regular monitoring helps catch problems early, before serious liver damage occurs.
If you have PFIC Type 3, you carry two copies of the mutated ABCB4 gene. Your children will inherit at least one copy, making them carriers. If your partner is also a carrier, each child has a 50% chance of being a carrier and a 25% chance of having PFIC Type 3. Genetic counseling can help you understand your family's specific risks and testing options.
When bile flow is blocked, bile acids build up in your blood and skin. These bile acids irritate nerve endings and cause severe itching, especially at night. The itching can be one of the most difficult symptoms to manage. Medications like antihistamines, rifampin, or cholestyramine can help, though they do not work for everyone.
Worsening symptoms include increased jaundice, more severe itching, new abdominal swelling, and confusion. Blood tests may show rising liver enzymes, bilirubin, or bile acids. Signs of advanced liver disease include easy bruising, nosebleeds, vomiting blood, and fluid retention. If you notice any of these changes, contact your doctor right away for evaluation and possible treatment adjustments.