Congenital bile acid synthesis defect 6 is a rare genetic condition that affects how the liver makes bile acids. Babies and young children with this condition often have jaundice, pale stools, poor growth, itching, or belly swelling. Without treatment it can lead to progressive liver damage, but early diagnosis and care can improve outcomes. Treatment usually includes specific bile acid replacement and nutrition support, and doctors monitor liver health over time. Not everyone will have the same experience, and many living with congenital bile acid synthesis defect 6 do well with ongoing care.
Overview
Congenital bile acid synthesis defect 6Symptoms
Early signs of congenital bile acid synthesis defect 6 appear in infancy: prolonged jaundice, pale or greasy stools, dark urine, poor growth, and itchy skin. Doctors may note enlarged liver and low fat‑soluble vitamins, leading to easy bruising or rickets.
Outlook and prognosis
Many living with congenital bile acid synthesis defect 6 do well when treatment starts early, as replacing missing bile acids can protect the liver and ease symptoms. Growth, energy, and vitamin levels often improve over months. Regular follow-up helps track liver health and adjust care.
Causes and risk factors
Congenital bile acid synthesis defect 6 stems from harmful changes in a bile‑acid–producing gene and is typically autosomal recessive. Risk is higher when both parents are carriers, with family history or consanguinity; environment or lifestyle do not cause it.
Genetic influences
Genetics are central in congenital bile acid synthesis defect 6, which stems from inherited changes in a single gene affecting bile acid production. Most cases are autosomal recessive, so both parents carry a variant. Genetic testing confirms diagnosis and guides family planning.
Diagnosis
Doctors suspect it from early cholestasis, poor growth, or fat-soluble vitamin problems. Diagnosis of Congenital bile acid synthesis defect 6 relies on specialized urine bile acid analysis, liver and blood tests, and imaging, with genetic tests confirming the cause.
Treatment and drugs
Treatment for congenital bile acid synthesis defect 6 focuses on replacing missing bile acids to improve digestion and protect the liver. Doctors often use oral primary bile acid therapy, adjust fat-soluble vitamin supplements, and monitor growth, labs, and imaging. Some may need nutrition support or, rarely, liver transplant if damage progresses.
Symptoms
In the first months, many babies develop yellowing of the skin and eyes, pale or gray stools, and trouble gaining weight. These early features of Congenital bile acid synthesis defect 6 relate to problems digesting fat and can also lead to shortages of vitamins A, D, E, and K. Features vary from child to child and can change over time.
Yellowing of the skin and the whites of the eyes can appear in the first weeks. It happens when bile builds up in the body. Many families spot this in natural light.
Stools may look very light or gray, and urine can be darker than usual. This means little bile is reaching the gut.
Babies may have trouble gaining weight despite regular feeds. In Congenital bile acid synthesis defect 6, this often ties back to difficulty absorbing fat and calories.
Stools can be bulky, oily, and hard to flush. This points to fat not being absorbed well.
How people usually first notice Congenital bile acid synthesis defect 6?
Many families first notice something is off in the first weeks to months of life: a baby with prolonged jaundice, pale or gray (acholic) stools, dark urine, poor weight gain, or an enlarged belly from liver swelling. Doctors often pick up the first signs of congenital bile acid synthesis defect 6 during early check-ups or hospital visits for jaundice, when blood tests show liver injury and imaging or stool color raise concern, leading to specialized tests of bile acids. In some cases, how congenital bile acid synthesis defect 6 is first noticed is through newborn screening abnormalities or genetic testing prompted by persistent cholestasis that doesn’t improve with standard care.
Types of Congenital bile acid synthesis defect 6
Congenital bile acid synthesis defect 6 is a genetic condition with a few recognized clinical variants, which mainly reflect how severely bile acid production is disrupted and when symptoms start. The differences often show up in timing (infancy versus later childhood) and in how the liver, growth, and fat-soluble vitamin levels are affected. Not everyone will experience every type. People may notice different sets of symptoms depending on their situation.
Classic infantile form
Symptoms begin in early infancy with jaundice, poor weight gain, and pale, hard-to-flush stools. Doctors often find enlarged liver and signs of fat-soluble vitamin deficiencies. Early treatment can ease symptoms and support growth.
Later-onset childhood
Symptoms appear in later childhood with slower growth, belly discomfort, or itchy skin from liver irritation. There may be fewer early jaundice episodes, but vitamin deficiencies can still develop. Keeping track of types of congenital bile acid synthesis defect 6 can help tailor monitoring.
Mild/attenuated course
Symptoms are subtler with intermittent stomach upset, mild liver test changes, or delayed growth spurts. Some children are identified during family screening or after persistent vitamin D or K shortages. The balance of symptoms can shift over time.
What genetics can tell you about symptoms
People with congenital bile acid synthesis defect 6 often develop jaundice, pale stools, dark urine, poor growth, and itching because mutations in the SLC27A5 (FATP5) gene disrupt the liver’s ability to make normal bile acids. This buildup of toxic intermediates injures liver cells, leading to hepatomegaly and lab abnormalities.
Causes and risk factors
Congenital bile acid synthesis defect 6 is caused by inherited changes in a liver enzyme gene that block normal bile acid production. It is usually autosomal recessive, so a child is affected when both parents are carriers. Risk is higher in families with a history, when parents are related, or if a close relative had early symptoms of congenital bile acid synthesis defect 6. Genes set the stage, but environment and lifestyle often decide how the story unfolds. Liver infections, medicines that strain the liver, and poor nutrition can worsen liver stress and raise complication risk.
Environmental and biological risk factors
Congenital bile acid synthesis defect 6 is rare, and most risk rests in factors present before birth rather than day-to-day choices. Doctors often group risks into internal (biological) and external (environmental). There are no well-established environmental triggers unique to this condition, but some prenatal exposures can influence how the fetal liver and bile system form. Below are environmental and biological risk factors for congenital bile acid synthesis defect 6 that clinicians consider when reviewing a pregnancy history.
No specific environmental exposure has been confirmed to cause congenital bile acid synthesis defect 6. Current evidence points to primarily internal factors established before birth.
Poorly controlled diabetes before or in early pregnancy is linked with higher rates of congenital disorders overall. It has not been shown to specifically cause congenital bile acid synthesis defect 6.
High-dose vitamin A derivatives taken in early pregnancy can disrupt fetal liver development. No direct association with congenital bile acid synthesis defect 6 is proven, but these drugs are known teratogens.
Exposure to heavy metals or industrial solvents in early pregnancy can affect organ formation. Evidence does not show a specific tie to congenital bile acid synthesis defect 6.
Genetic risk factors
In congenital bile acid synthesis defect 6, harmful changes in a single gene disrupt bile acid production. Some risk factors are inherited through our genes, mainly the chance of receiving two nonworking copies—one from each parent. This follows an autosomal recessive pattern, so when both parents are carriers, each pregnancy has a 25% chance of an affected child. Understanding the genetic causes of congenital bile acid synthesis defect 6 can guide testing for you and your family.
Single-gene cause: Harmful variants in the gene that controls a key step in bile acid production lead to the disorder. These variants reduce or stop the enzyme’s activity needed to make normal bile acids.
Autosomal recessive pattern: A child is affected only if two nonworking copies are inherited, one from each parent. When both parents are carriers, each pregnancy has a 25% chance of congenital bile acid synthesis defect 6.
Silent carriers: People with one nonworking copy usually have no health problems. Their child’s risk depends on whether a partner also carries the same gene change.
Homozygous or compound: Some have the same variant on both copies of the gene (homozygous), while others have two different variants (compound heterozygous). Both patterns can cause congenital bile acid synthesis defect 6.
Variable expressivity: Even with the same gene changes, the age features are noticed and how severe they are can differ. This variability can reflect other genetic modifiers.
Shared ancestry risk: Parents who are closely related or come from a small, isolated community are more likely to carry the same rare variant. That raises the chance of a child with congenital bile acid synthesis defect 6.
Family recurrence: After one child is diagnosed, future pregnancies for the same parents carry a 25% risk of the condition. Unaffected siblings have a 50% chance of being carriers.
De novo changes rare: Most affected children inherit one variant from each carrier parent. New changes arising for the first time in the child on both gene copies are uncommon.
Lifestyle risk factors
Lifestyle habits do not cause Congenital bile acid synthesis defect 6, but they can influence fat absorption, vitamin status, liver strain, and day-to-day symptoms. Thoughtful nutrition and activity choices may improve energy, growth, and bone health while reducing complications. Here’s how lifestyle affects Congenital bile acid synthesis defect 6 and what to consider when thinking about lifestyle risk factors for Congenital bile acid synthesis defect 6.
Diets high in long-chain fats can worsen steatorrhea and nutrient losses when bile acid conjugation is impaired. Emphasizing medium-chain triglycerides can improve calorie uptake and ease digestive symptoms.
Inadequate intake or missed supplementation of vitamins A, D, E, and K can aggravate deficiencies common in this condition. Consistent, guided supplementation supports vision, bone health, immunity, and blood clotting.
Insufficient calories and protein can compound growth delays and hinder liver recovery. Regular, energy-dense meals and snacks help maintain weight and support healing.
Alcohol and hepatotoxic supplements or medications add stress to an already vulnerable liver. Avoiding alcohol and unvetted herbal products lowers the risk of liver inflammation and progression.
Risk prevention
Because congenital bile acid synthesis defect 6 is inherited, there isn’t a way to prevent the condition itself, but you can lower the chance of liver damage and long-term complications. Acting early—ideally in infancy—often protects growth, nutrition, and development. Prevention can mean both medical steps, like vaccines, and lifestyle steps, like exercise. Care is most effective when you work with a metabolic or liver specialist and keep regular follow-ups.
A genetics professional can explain inheritance and your family’s chances in future pregnancies. Carrier testing, prenatal testing, or IVF with embryo testing may be options for some families.
Early referral to a pediatric liver or metabolic team helps confirm the diagnosis and start treatment quickly. Starting bile acid therapy early can prevent ongoing liver injury and improve growth.
Noticing early symptoms of congenital bile acid synthesis defect 6—such as prolonged jaundice, pale or putty-colored stools, dark urine, or poor weight gain—can speed diagnosis and treatment. If these appear in a newborn or infant, seek medical care promptly.
Keep routine vaccines up to date and ensure hepatitis A and B vaccination. This lowers the risk of infections that can strain the liver.
Transmission
Congenital bile acid synthesis defect 6 is a genetic condition, not an infection, so it doesn’t spread between people through touch, coughing, sex, or shared items. It’s usually inherited in an autosomal recessive pattern: each parent is typically a healthy carrier, and with each pregnancy there’s a 25% chance the child will have the condition, a 50% chance they’ll be a carrier, and a 25% chance they’ll inherit neither change. Very rarely, a new gene change can arise for the first time in a child, but most cases happen when both parents carry the same gene change. If this runs in your family, a genetics visit can explain how Congenital bile acid synthesis defect 6 is inherited and discuss testing for partners, siblings, and future pregnancies, including the genetic transmission of Congenital bile acid synthesis defect 6.
When to test your genes
Congenital bile acid synthesis defect 6 is genetic, so testing is most useful if there’s persistent cholestasis, fat‑soluble vitamin deficiency, or unexplained liver dysfunction in infancy or childhood, especially with a family history. Early diagnosis guides targeted bile acid therapy and nutrition. Siblings and future pregnancies may also warrant testing and counseling.
Diagnosis
For many families, the first clues are day-to-day issues like prolonged jaundice, pale stools, poor weight gain, or easy bruising from low vitamins. Early and accurate diagnosis can help you plan ahead with confidence. For Congenital bile acid synthesis defect 6, doctors look at the pattern of symptoms and lab findings, then confirm with specialized testing. The genetic diagnosis of Congenital bile acid synthesis defect 6 is usually made by combining bile acid studies with DNA testing.
Doctors review feeding, growth, stool color, itching, and family history, then check for jaundice and an enlarged liver. These clinical features guide which tests to order next.
A blood panel checks bilirubin, liver enzymes, and clotting. Results can suggest cholestasis and help rule out more common liver diseases.
Blood tests look at vitamins A, D, E, and K, which can be low when bile acids are missing. Finding deficiencies supports the suspicion of a bile acid synthesis problem.
A specialized urine or blood test uses mass spectrometry to look for unusual bile acid patterns. In bile acid synthesis defects, total bile acids may be normal or low but the types are abnormal.
Stages of Congenital bile acid synthesis defect 6
Congenital bile acid synthesis defect 6 does not have defined progression stages. This condition tends to vary from person to person, and changes over time are influenced by age, nutrition, and how quickly treatment starts rather than a predictable step-by-step course. Doctors look for patterns such as early symptoms of congenital bile acid synthesis defect 6—like prolonged newborn jaundice, pale or gray stools, poor weight gain, and fat‑soluble vitamin shortages—along with liver blood tests and a urine bile acid profile. Different tests may be suggested to help confirm the diagnosis, including genetic testing and ongoing monitoring of liver function to guide care.
Outlook and prognosis
Looking ahead can feel daunting, but most children with congenital bile acid synthesis defect 6 (CBASD6) can do well when the condition is found early and treated consistently. Early care can make a real difference, especially before significant liver scarring sets in. Many people ask, “What does this mean for my future?”, and the short answer is that outcomes range widely: some children stabilize and grow normally on bile acid therapy and nutrition support, while others develop progressive liver disease that may lead to cirrhosis.
Prognosis refers to how a condition tends to change or stabilize over time. In CBASD6, medicines that replace or modulate bile acids often improve jaundice, itching, and growth within weeks to months, and they can lower liver enzymes and help vitamins absorb better. If treatment starts late, or if the liver is already badly scarred, risks rise for portal hypertension, infections, and, in some cases, liver failure. When bile acid therapy does not control the disease, liver transplant can be lifesaving and offers good long‑term survival in many centers.
Everyone’s journey looks a little different. Early symptoms of congenital bile acid synthesis defect 6—such as prolonged jaundice, pale stools, poor weight gain, or severe itching—should prompt evaluation, because catching the condition early tends to improve the long‑term outlook. Most children who respond to therapy can attend school, play sports with pacing, and lead active lives, though they’ll need regular labs, imaging, and fat‑soluble vitamin checks. Mortality today is largely linked to advanced liver disease before diagnosis or to complications while waiting for transplant; with modern care and timely transplant when needed, survival into adulthood is common. Talk with your doctor about what your personal outlook might look like.
Long-term effects
For many, day-to-day life is shaped by how the liver processes bile, absorbs nutrients, and keeps energy steady over time. Long-term effects vary widely, and may change from infancy to adolescence and adulthood. With congenital bile acid synthesis defect 6, outlook depends on how early it’s recognized and how well bile flow and vitamins are supported. Some features ease as the liver stabilizes, while others reflect chronic liver stress or past vitamin shortages.
Ongoing inflammation can lead to fibrosis and sometimes cirrhosis over the years. This can raise the risk of liver-related complications in adolescence or adulthood.
Scarring can slow blood flow through the liver, causing high pressure in the portal vein. This may lead to enlarged spleen and swollen veins in the esophagus.
Trouble absorbing fats can make gaining weight and height harder in childhood. Some catch up later, but others remain on the smaller side.
Low vitamins A, D, E, and K can have lasting effects on bones, vision, nerves, and blood clotting. Regular levels often track closely with long-term wellbeing in congenital bile acid synthesis defect 6.
How is it to live with Congenital bile acid synthesis defect 6?
Living with congenital bile acid synthesis defect 6 often means working closely with a liver specialist, following a consistent medication plan to replace missing bile acids, and sticking to a nutrition strategy that supports growth and prevents vitamin deficiencies. Day to day, many manage fatigue, tummy discomfort, or itching during flares, along with regular lab checks and imaging to watch liver health; with treatment, energy and growth often improve. Families and caregivers become part of the routine—helping with meds, meals, and appointments—and may feel the emotional weight of uncertainty, but clear care plans and specialist support usually ease that burden. Over time, many people build steady rhythms that allow school, work, and family life to move forward with fewer interruptions.
Treatment and drugs
Treatment for congenital bile acid synthesis defect 6 focuses on replacing the missing or low bile acids and protecting the liver. Doctors often prescribe bile acid medicines such as cholic acid or chenodeoxycholic acid to restore the bile “flow,” improve fat absorption, and lower toxic byproducts that can damage the liver. A doctor may adjust your dose to balance benefits and side effects, with regular blood tests, urine bile acid profiles, and liver imaging to track response. Alongside medical treatment, lifestyle choices play a role: some people need nutrition support, including medium‑chain triglycerides, added calories, and fat‑soluble vitamin supplements (A, D, E, K). If severe liver scarring develops despite therapy, liver transplantation may be considered, and lifelong follow‑up with a metabolic or liver specialist is essential.
Non-drug treatment
Daily care for Congenital bile acid synthesis defect 6 focuses on nutrition, itch relief, growth, and protecting the liver. Alongside medicines, non-drug therapies can steady nutrition, support growth, and ease itching. Early symptoms of Congenital bile acid synthesis defect 6—like greasy stools and poor weight gain—often improve when fat absorption is supported.
High-calorie, nutrient-dense meals help catch up growth and maintain energy. A pediatric dietitian can tailor meals to your child’s needs and food preferences. Regular weight and length checks guide adjustments.
Medium-chain fats are easier to absorb when bile flow is low, so adding MCT oil or MCT-containing formulas can reduce greasy stools. This can improve energy and weight gain. Monitor tolerance and stool changes with your care team.
Vitamins A, D, E, and K often need extra supplementation to prevent vision, bone, nerve, and bleeding problems. Doctors check blood levels and adjust doses over time. Liquid or drop forms can make daily dosing easier.
If eating by mouth is too hard, temporary tube feeding (nasogastric or gastrostomy) can deliver calories safely. This helps protect growth while your child builds feeding skills. Caregivers can help make lifestyle changes feel more manageable.
Your genes may have an impact on how drugs work for you
Genes can change how the body processes bile-acid–related medicines, affecting dose needs and risk of side effects. Variants in enzymes that build or break down bile acids can make standard therapies less effective, so care teams may adjust treatment or monitor more closely.
Pharmacological treatments
Treatment focuses on replacing the missing bile acids, protecting the liver, and easing symptoms day to day. Recognizing early symptoms of congenital bile acid synthesis defect 6 can help start therapy sooner and may prevent complications. First-line medications are those doctors usually try first, based on safety and how well they work. Care is guided by specialist centers, with regular blood tests and sometimes stool or urine studies to track progress.
This is the main replacement therapy that can normalize bile flow, improve jaundice, and support growth. Dosing may be increased or lowered gradually to meet treatment goals and limit side effects. Regular monitoring of liver enzymes and bile acid profiles is important.
In select situations, specialists may consider CDCA when cholic acid is not suitable or not fully effective. It requires close monitoring because it can irritate the liver, especially in young children. Use is individualized and guided by experienced centers.
UDCA may help with cholestasis symptoms, but it does not replace the missing bile acids in CBAS6. Many will not benefit from UDCA as a primary treatment, so it’s typically avoided unless a specialist recommends it. If used, liver tests should be followed closely.
Rifampin, cholestyramine, or naltrexone can ease troublesome itching from cholestasis. Drugs that target symptoms directly are called symptomatic treatments. If cholestyramine is used, take it at least 4 hours apart from cholic acid so it doesn’t block absorption.
Genetic influences
Congenital bile acid synthesis defect 6 is usually caused by inherited changes in a single liver gene that helps the body make bile acids. This follows an autosomal recessive pattern, meaning a child is affected when they receive one nonworking copy from each parent. A “carrier” means you hold the gene change but may not show symptoms. When two carriers have a baby, each pregnancy has a 25% chance of congenital bile acid synthesis defect 6, a 50% chance the child will be a carrier, and a 25% chance of having no gene change. Because carriers are healthy, some families won’t notice any history until more than one sibling is affected; severity and age at diagnosis can also vary. Genetic testing can confirm the genetic causes of congenital bile acid synthesis defect 6 and can help guide care and future family planning, including testing options for relatives.
Is Congenital bile acid synthesis defect 6 genetic?
Genetics are central in congenital bile acid synthesis defect 6, which stems from inherited changes in a single gene affecting bile acid production. Most cases are autosomal recessive, so both parents carry a variant. Genetic testing confirms diagnosis and guides family planning.
Pharmacogenetics—how genetics influence drug effects
In Congenital bile acid synthesis defect 6, the specific gene change disrupts the step that “activates” bile acids, so genetics directly guide which bile acid medicines are used and how they’re dosed. Many people are treated with prescription cholic acid to restore a healthier bile acid mix and dial down the body’s overproduction of harmful byproducts; doctors adjust the dose by weight and by following liver tests and urine bile acid profiles. Genetic testing for Congenital bile acid synthesis defect 6 helps confirm the exact enzyme problem, which in turn steers choices such as using cholic acid, avoiding chenodeoxycholic acid in certain subtypes, and not relying on ursodeoxycholic acid as a stand‑alone therapy. Not every difference in response is genetic, but factors like age, liver scarring, nutrition, and other medications can shift how well bile acid therapy works. Your genetic results can also inform care for siblings and future pregnancies, allowing treatment to start early and potentially prevent growth delays and vitamin deficiencies.
Interactions with other conditions
When another illness strains the liver—like a viral infection or gallbladder inflammation—jaundice, itching, and poor appetite from Congenital bile acid synthesis defect 6 can flare and feel harder to control. Early symptoms of Congenital bile acid synthesis defect 6 can also be hard to separate from signs of another liver or gut problem, especially during bouts of diarrhea or when appetite dips. Conditions that reduce fat absorption, such as chronic pancreatitis or untreated celiac disease, can compound shortages of vitamins A, D, E, and K in CBAS6, raising the risk of weak bones, vision changes, nerve symptoms, and easy bruising. A condition may “exacerbate” (make worse) symptoms of another. Medicines that rely on the liver for processing—such as certain antibiotics, seizure treatments, or herbal supplements—may stress the liver further, so dosing and monitoring often need adjustment. Bleeding or clotting disorders, or use of blood thinners, deserve special attention because vitamin K deficiency from CBAS6 can tilt the balance toward bleeding, making coordinated care and regular lab checks important.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
History
Throughout history, people have described infants who failed to gain weight, looked deeply jaundiced, and had pale stools, long before anyone knew why their livers were struggling. Families and communities once noticed patterns—one baby after another in the same family becoming ill early in life—without a clear explanation. Doctors could see enlarged livers and poor growth, but standard tests for common liver diseases were often unrevealing, which left caregivers and clinicians searching.
First described in the medical literature as unusual forms of infant cholestasis that did not fit known causes, these cases slowly pointed toward a hidden problem in bile production. In the late 20th century, biochemical studies of blood, urine, and liver tissue began to show distinctive fingerprints of missing or faulty bile acids. Initially understood only through symptoms, later work traced several rare conditions to specific steps in the body’s bile acid “assembly line.” Congenital bile acid synthesis defect 6 emerged from this effort as one of a group of inborn errors where the liver cannot make the bile acids it needs to digest fats and carry waste out of the body.
With each decade, tools improved. Mass spectrometry allowed scientists to detect abnormal bile-related molecules, and targeted treatments with certain bile acids helped confirm the diagnosis when infants improved. Advances in genetics then identified disease-causing changes in the gene responsible for this particular step, providing a precise label for congenital bile acid synthesis defect 6 and explaining why it could run in families. This genetic clarity also showed that early symptoms of congenital bile acid synthesis defect 6 can overlap with other liver problems, which is why some children were missed in the past.
Over time, descriptions became more specific: newborns or young infants with persistent jaundice, fat-soluble vitamin deficiencies, poor weight gain, and sometimes an enlarged spleen or liver on exam. As medical science evolved, clinicians recognized that not every child follows the same course—some become ill within weeks, while others present later in infancy. This variability, once a source of confusion, now guides earlier testing in babies with unexplained cholestasis.
Looking back helps explain how care changed. What once led to repeated hospital stays and liver biopsies now more often leads to a focused evaluation that includes specialized bile acid testing and genetic analysis. These historical steps opened the door to earlier diagnosis and treatment, which can prevent complications, support growth, and, for many living with congenital bile acid synthesis defect 6, greatly improve long-term health.