FATTY ACID DISORDER

Disorder name: Short chain acyl-CoA dehydrogenase deficiency
Acronym: SCADD
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• What is SCADD?
• What causes SCADD?
• If SCADD is not treated, what problems occur?
• What is the treatment for SCADD?
• What happens when SCADD is treated?
• What causes the SCAD enzyme to be absent or not working correctly?
• How is SCADD inherited?
• Is genetic testing available?
• What other testing is available?
• Can you test during a future pregnancy?
• Can other members of the family have SCADD or be carriers?
• Can other family members be tested?
• How many people have SCADD?
• Does SCADD happen more often in a certain ethnic group?
• Does SCADD go by any other names?
• Where can I find more information?

This fact sheet contains general information on SCADD.  Every child with SCADD is different and some of this information may not apply to your child specifically. Not all is known about SCADD and, at present, there is no standard treatment plan. Certain treatments may be recommended for some children but not others. Children with SCADD should be followed by a metabolic doctor in addition to their primary doctor.

WHAT IS SCADD?

SCADD stands for “short chain acyl-CoA dehydrogenase deficiency.” It is one type of fatty acid oxidationThis is the process used by the body to change fatty acids, the building blocks of fat, into energy. It happens in the mitochondria – the small energy-producing parts found in each cell of the body. disorder. Some people with SCADD cannot break down fat into energy for the body. However, most babies with newborn screening results showing SCADD never have symptoms.

Fatty Acid Oxidation Disorders: Fatty acid oxidation disorders (FAODs)This is a group of rare inherited conditions. FAODs are caused by missing or non-working enzymes. Normally, many enzymes are used by the body to break down fat into energy. In people with FAODs, one of these enzymes is not working and fat cannot be used for energy. If these conditions are not treated, they can lead to serious health problems. are a group of rare inheritedAcquiring a trait from one’s parents. Most traits, such as eye color or hair color, are inherited from a parent through genes. conditions. They are caused by enzymes that do not work properly. A number of enzymesA molecule that helps chemical reactions take place. For example, enzymes in the stomach speed up the process of breaking down food. Each enzyme can participate in many chemical reactions without changing or being used up. are needed to break down fats in the body (a process called fatty acid oxidation). Problems with any of these enzymes can cause a fatty acid oxidation disorder. People with FAODs cannot properly break down fatFat is one of the three main nutrients in food (carbohydrates, fat, protein). Some foods that contain fat are butter, margarine, oils, nuts, meats, poultry, fish and some dairy products. Extra calories from food are stored as body fat. Stored body fat provides the body with a reserve supply of energy. from either the food they eat or from fat stored in their bodies. The symptoms and treatment vary between different FAODs. They can also vary from person to person with the same FAOD. See the fact sheets for each specific FAOD. FAODs are inherited in an autosomal recessive manner and affect both males and females.

WHAT CAUSES SCADD?

SCADD is caused by problems with an enzyme called “short chain acyl-CoA dehydrogenase” (SCAD). In people with SCADD, this enzyme is either missing or not working properly. This enzyme’s job is to break down certain fats from the food we eat into energy. It also breaks down fat already stored in the body.

Energy from fat keeps us going whenever our bodies run low of their main source of energy, a type of sugar called glucoseThis is a type of sugar made from the carbohydrates in food. Glucose is found in the blood. It is the main source of energy for the body and brain.. Our bodies rely on fat when we don’t eat for a stretch of time – like when we miss a meal or when we sleep.

Some people with SCADD cannot properly break down fat for energy. However, most people with SCADD do not seem to have this problem and do not ever develop symptoms.

IF SCADD IS NOT TREATED, WHAT PROBLEMS OCCUR?

SCADD is highly variable and not well understood. Most babies found to have SCADD through newborn screeningA screening test that looks for different disorders using a small sample of blood taken from a newborn’s heel. A positive or abnormal newborn screening result means that there are slight differences that were found in the baby’s blood, and further testing is needed to figure out if the baby has a metabolic disorder. never have symptoms. In fact, so far, there have been only about 20 people with SCADD reported to have health effects. Things that cause stress, such as lack of sleep, going without food for too long, illness, or infection are thought to trigger episodes of illness called metabolic crisis in some children but not others.

For the small number of people with SCADD who show effects, the condition occurs in two different types: one found in infants, the other found in adults.

SCADD in infants
This type of SCADD is found in newborns and infants. Symptoms, when they happen, often start between the first week and 3 months of life.

Some of the first symptoms of a metabolic crisisThis is a serious health condition caused by low blood sugar and the build-up of toxic substances in the blood. Symptoms of a metabolic crisis are poor appetite, nausea, vomiting, diarrhea, extreme sleepiness, irritable mood and behavior changes. If not treated, breathing problems, seizures, coma, and sometimes even death can occur.Metabolic crises happen more often in people with certain metabolic disorders (some fatty acid oxidation disorders, amino acid disorders, and organic acid disorders). They are often triggered by things like illness or infection, going without food for a long time, and, in some cases, heavy exercise. are:

• extreme sleepiness
• behavior changes
• irritable mood
• poor appetite

Other symptoms then follow:

• fever
• diarrhea
• vomiting
• increased levels of acidic substances in the blood, called metabolic acidosisThis happens when acidic substances build up in the blood. It can cause rapid breathing, confusion, and extreme sleepiness. If not treated, it may lead to shock, coma or death.

If a metabolic crisis is not treated, a child with SCADD can develop:

• breathing problems
• seizuresThese are also called "convulsions" or "fits." During a seizure, a person loses consciousness and control of his or her muscles. It may also cause involuntary movements. Seizures can happen for many reasons. Some causes are metabolic disorders, a metabolic crisis, brain injury, and infection.
• comaThis is a sleep-like condition from which a person cannot be awakened. People in a coma are unconscious. A coma can be caused by many things. Two causes are untreated low blood sugar (hypoglycemia) and a metabolic crisis., sometimes leading to death

Other effects of SCADD seen in some infants and children are:

• poor weight gain
• delays in learning
• delays in walking and other motor skills
• hyperactivityThis refers to children who are unusually overactive. These children have serious problems sitting still. They tend to fidget and run around much more than usual. Some children with hyperactivity need treatment. They may be helped by behavior treatment, medication or both of these therapies.
• decreased or increased muscle toneIn order to hold our posture and control our movements, a certain amount of tension is needed in our muscles. This tension is called “muscle tone.” People with hypotonia have too little tension in their muscles and appear “floppy.” People with hypertonia have too much tension in their muscles and have problems with tight, rigid muscles and joints.
• muscle weakness
• enlarged liver
• enlarged spleenThis is an organ located behind the stomach. It gets rid of old blood cells and helps fight infection. The spleen can enlarge in people with cirrhosis or with certain metabolic disorders.

Symptoms of a metabolic crisis often happen after having nothing to eat for more than a few hours. Symptoms are also more likely when a child with SCADD gets sick or has an infection.

Many children with this condition have never had any effects and may only be found to have SCADD after a brother or sister has been diagnosed. Most children diagnosed through newborn screeningThe process of testing for disease in a person who does not show signs of having the disease (nonsymptomatic or asymptomatic person). The goal of screening is to catch the disease in its early stages. never develop any symptoms related to SCADD.

SCADD in adults
The second type of SCADD is found in adults. The adult type of SCADD affects just the muscles. It can cause ongoing muscle problems, pain, and weakness. Adults with SCADD can also have episodes of nausea, vomiting, and shortness of breath. The muscle problems often get worse after heavy exercise or exertion.

WHAT IS THE TREATMENT FOR SCADD?

Your baby’s primary doctor may work with a metabolic doctor to care for your child. Your doctor may also suggest that you meet with a dietician familiar with SCADD.

Certain treatments may be advised for some children but not others. Babies found to have SCADD on newborn screening, but who have not shown any effects, may not need treatment. When necessary, treatment is usually needed throughout life. The following are treatments recommended for some, but not all, children with SCADD:

1.  Avoid going a long time without food 
Some babies and young children with SCADD may need to eat often to avoid a metabolic crisis. These children should not go without food for more than four to six hours. In fact, some babies may need to eat even more often than this. They may also need to be fed during the night. Your metabolic doctorThis is a doctor or medical geneticist who has special training in diagnosing and treating metabolic disorders. They often work in university hospitals or large medical centers. will tell you whether your child needs to be fed more often than normal. If so, you will receive an eating plan tailored to your child’s specific needs.

Your metabolic doctor will continue to advise you on how often your child should eat as he or she gets older. When they are well, most teens and adults with SCADD can go without food for up to 12 hours. People who have had symptoms may need to continue the other treatments throughout life.

2.  Diet
A low fat, high carbohydrate food plan may be advised for some children with SCADD. CarbohydratesThis is one of the three types of nutrients in food (carbohydrates, fats, proteins). Sugars and starches are the most important types of carbohydrates. They are broken down by the body into glucose, the main source of energy for the body. Carbohydrates are found in foods such as: bread, cereal, pasta, grains, fruits and vegetables. Milk and dairy products, fruit drinks, sugar, candy, and sweet desserts also contain carbohydrates. give the body many types of sugar that can be used as energy. In fact, for children needing this treatment, most food in the diet should be carbohydrates (bread, pasta, fruit, vegetables, etc.) and protein (lean meat and low-fat dairy foods). Any diet changes should be made under the guidance of a dieticianThis is a person with special training in food and nutrition. A registered dietician (RD) has met the necessary educational requirements and has passed a national examination. If your child has a metabolic disorder, it is important for you to work with a registered dietician. They help create healthy food plans for people with metabolic disorders or other special needs. familiar with SCADD.

Ask your doctor whether or not your child needs to have any changes in his or her diet.

3.  L-CarnitineThis is a natural substance found in muscle cells. It helps the body make energy from the fat in food and the fat stored in the body. It also helps the cells get rid of harmful wastes made during the breakdown of fat. Carnitine supplements may be used as a treatment for some metabolic disorders. and RiboflavinThis is a one type of B vitamin (vitamin B2). It helps change carbohydrates, protein, and fat into energy for the body. Some foods high in riboflavin are dairy products, yogurt, cheese, meats, poultry, whole and enriched grains, and green vegetables. Some children with metabolic disorders may be helped by taking riboflavin supplements.
Some children may be helped by taking L-carnitine. This is a safe and natural substance that helps the body create energy. It also helps the body get rid of harmful wastes. Your doctor will decide whether or not your child needs L-carnitine.  Unless you are advised otherwise, use only L-carnitine prescribed by your doctor.

A few children with SCADD have been helped by riboflavin (vitamin B2) supplements. Ask your metabolic doctor whether your child should take riboflavin.

Do not use any medications or supplements without checking with your doctor.

4.  Call your doctor at the start of any illness
Call your health care provider when your child has any of the following:

• poor appetite
• low energy or excessive sleepiness
• vomiting
• diarrhea
• an infection
• a fever
• persistent muscle pain or weakness

Some children with SCADD may need to eat extra starchy food and drink more fluids during an illness – even if they may not feel hungry – to prevent a metabolic crisis. Children who are sick often don’t want to eat. If they won’t or can’t eat, some children with SCADD may need to be treated in the hospital to prevent problems. If needed, your doctor will give you a ‘sick day’ plan for you to follow during illness or other times when your child will not eat.

WHAT HAPPENS WHEN SCADD IS TREATED?

It is not known how effective treatment is in preventing problems. Treatment may help prevent or control symptoms in some children. Children who need treatment and are treated early may be able to live healthy lives with typical growth and development. Some children, though, may continue to have learning delays, muscle weakness, and other health problems despite treatment.

WHAT CAUSES THE SCAD ENZYME TO BE ABSENT OR NOT WORKING CORRECTLY?

Genes tell the body how to make enzymes. The ACADS gene instructs the body to make the SCAD enzyme. Everyone has two copies of the ACADS gene. People with SCADD have changes, also called variantsA variant is a change or alteration in a person’s DNA sequence. Variants can happen in genes and affect how the gene functions. There are different types of variants – they can be non-problem causing (benign), disease-causing (pathogenic) or of unknown significance. The term variants is now used in place of the term mutation., in both copies of their ACADS genesA segment of DNA that contains the instructions to make a specific protein (or part of a protein). Genes are contained on chromosomes. Chromosomes, and the genes on those chromosomes, are passed on from parent to child. Errors in the DNA that make up a gene are called variants and can lead to diseases. that cause them to not work correctly.

HOW IS SCADD INHERITED?

SCADD is inherited in an autosomal recessive manner. It affects both boys and girls equally.

Everyone has a pair of genes that make the SCAD enzyme. In children with SCADD, neither of their ACADS genes works correctly. These children inherit one non-working ACADS gene each parent.

Parents of children with SCADD rarely have the disorder. Instead, each parent has a single non-working ACADS gene. They are called carriersA person who has one copy of a gene mutation for a particular autosomal recessive disorder (remember genes come in pairs). Carriers are not affected by the disorder. However, they can pass on the gene variant to their children. Children who inherit two such gene variants will be affected by the disorder. The term variants is now used in place of the term mutation.. Carriers do not have SCADD because their other ACADS gene is working correctly.

When both parents are carriers, there is a 25% chance in each pregnancy for the child to have SCADD. There is a 50% chance for the child to be a carrier, just like the parents. And, there is a 25% chance for the child to have two working genes.

GeneticRelating to (or due to) genes and heredity or the field of studying genes and heredity. counseling is available to families who have children with SCADD. Genetic counselors can answer your questions about how SCADD is inherited, choices during future pregnancies, and how to test other family members. Ask your doctor about a referral to a genetic counselorThese are health care providers who have special training in genetic conditions. They help families understand genetic disorders and how they are passed down. Genetic counselors offer information and support to people who have genetic conditions in their families or are concerned that they may have a child with an inherited disorder..

IS GENETIC TESTING AVAILABLE?

Genetic testing for SCADD can be done on a blood sample. Genetic testing, also called DNA testing, looks for changes (variants) in the pair of genes that cause SCADD. DNADeoxyribonucleic acid (DNA) is a molecule found in the chromosomes that carries genetic information. DNA is composed of four units (called bases) that are designated A, T, G, and C. The sequence of the bases spell out instructions for making all of the proteins needed by an organism. A gene is a section of DNA that holds the instructions for a specific protein. A change in one or more of the DNA bases making up a gene is called a mutation. Some mutations change the protein instructions and can lead to particular health problems or disorders. Each parent passes half of their chromosomes, and thus half of their DNA instructions, onto their children. It is these instructions that cause certain traits, such as eye or hair color, to be inherited. testing is often used to diagnose SCADD in children. In some affected children, both gene changes can be found. However, in other children, neither or only one of the two gene changes can be found, even though we know they are present.

DNA testing results will not help establish if your child will develop symptoms from SCADD. However, it can be helpful for carrier testing or prenatal diagnosis, discussed below. Talk with your metabolic doctor or genetic counselor if you have questions about DNA testing for SCADD.

WHAT OTHER TESTING IS AVAILABLE?

SCADD can be confirmed by an enzyme test using a blood or skin sample. Talk to your doctor or your genetic counselor if you have questions about testing for SCADD.

CAN YOU TEST DURING A FUTURE PREGNANCY?

If both gene changes have been found in your child with SCADD, DNA testing can be done during future pregnancies. The sample needed for this test is obtained by either CVS or amniocentesisThis is a test done during pregnancy. A needle is used to remove a small sample of fluid from the sac around the fetus. The sample can be used to test for certain genetic disorders in the fetus. Amniocentesis to test for genetic conditions is usually done between 13 and 20 weeks of pregnancy..

If DNA testing would not be helpful, testing during pregnancy can be attempted by performing an enzyme test on fetal cellsThe smallest living unit. Cells make up all organs and tissues in multi-cellular organisms, like humans. They can also live independently, as in bacteria and other microorganisms. At a minimum, a cell is surrounded by a membrane, contains DNA at some stage in its life, and is able to replicate itself into two equal parts.. Again, the sample needed for these tests is obtained by either CVSThis is a special test done early in pregnancy. During CVS, a small sample of the placenta is removed for testing. This sample can be used to test for certain genetic disorders in the fetus. CVS is usually done between 10 and 12 weeks of pregnancy. or amniocentesis.

Parents may either choose to have testing during pregnancy or wait until birth. Parents may also choose to use assisted reproductive techniques to decrease the chance that their future children would have SCADD. A genetic counselor can talk to you about your choices and answer other questions about prenatal testing or testing your baby after birth.

CAN OTHER MEMBERS OF THE FAMILY HAVE SCADD OR BE CARRIERS?

Having SCADD
The brothers and sisters of an affected baby have a chance of having SCADD, even if they haven’t had symptoms. Talk with your doctor or genetic counselor about testing your other children for SCADD.

SCADD Carriers
Brothers and sisters who do not have SCADD still have a chance to be carriers like their parents. Except in special cases, carrier testing should only be done in people over 18 years of age.

If you are a parent of a child with SCADD, your brothers and sisters have a 50% chance to be a SCADD carrier. It is important for other family members to be told that they could be carriers. There is a small chance they are also at risk to have children with SCADD.

Some states do not offer newborn screening for SCADD. However, expanded newborn screening is available through private labs for babies born in states that do not screen for this condition. Your healthcare provider or genetic counselor can help you obtain expanded newborn screening.

When both parents are carriers, newborn screening results are not sufficient to rule out SCADD in a newborn baby. In this case, special diagnostic testing should be done in addition to newborn screening.

During pregnancy, women carrying fetuses with SCADD may be at increased risk to develop serious medical problems. Some women carrying fetuses with Fatty Acid Oxidation Disorders have developed:

• excessive vomiting
• abdominal pain
• high blood pressure
• jaundiceThis is a yellow color to the skin and whites of the eyes. It is often a sign of liver damage.
• abnormal fat storage in the liver
• severe bleeding

All women with a family history of SCADD should share this information with their obstetricians and other health care providers before and during any future pregnancies. Knowing about these risks allows better medical care and early treatment if needed.

CAN OTHER FAMILY MEMBERS BE TESTED?

Diagnostic testing
Brothers and sisters can be tested for SCADD using a blood or skin sample.

Carrier testing
If both gene changes have been found in your child with SCADD, other family members can have DNA testing to see if they are carriers.

If DNA testing would not be helpful, other methods of carrier testing may be available. Your metabolic doctor or genetic counselor can answer your questions about carrier testing.

HOW MANY PEOPLE HAVE SCADD?

SCADD was originally thought to be very rare. However, newborn screening for this disorder revealed that SCADD is more common than previously believed and is thought to affect between 1 in 35,000 to 50,000 newborns.

DOES SCADD HAPPEN MORE OFTEN IN A CERTAIN ETHNIC GROUP?

SCADD does not happen more often in any specific race, ethnic group, geographical area, or country.

DOES SCADD GO BY ANY OTHER NAMES?

SCADD is also sometimes called:

• SCAD deficiency
• ACADS deficiency
• SCADH deficiency

WHERE CAN I FIND MORE INFORMATION?

Fatty Oxidation Disorders (FOD) Family Support Group
http://www.fodsupport.org

Organic Acidemia Association
http://www.oaanews.org

United Mitochondrial Disease Foundation
http://www.umdf.org

Metabolic Support UK
https://www.metabolicsupportuk.org

Genetics Home Reference
https://ghr.nlm.nih.gov/condition/short-chain-acyl-coa-dehydrogenase-deficiency

Baby’s First Test
http://www.babysfirsttest.org

DOCUMENT INFO:

Created by:	www.newbornscreening.info
Reviewed by:	HI, CA, OR, and WA metabolic specialists
Review date:	May 4, 2020 July 13, 2013 April 18, 2011 September 31, 2007
Update on:	May 4, 2020

DISCLAIMER:

THIS INFORMATION DOES NOT PROVIDE MEDICAL ADVICE. All content (“Content”), including text, graphics, images and information are for general informational purposes only. You are encouraged to confer with your doctor or other health care professional with regard to information contained on this information sheet. After reading this information sheet, you are encouraged to review the information carefully with your doctor or other healthcare provider. The Content is not intended to be a substitute for professional medical advice, diagnosis or treatment. NEVER DISREGARD PROFESSIONAL MEDICAL ADVICE, OR DELAY IN SEEKING IT, BECAUSE OF SOMETHING YOU HAVE READ ON THIS INFORMATION SHEET. This project is supported by a grant from the MaternalHaving to do with the mother. and Child Health Bureau, Health Resources and Service Administration, Genetic Services Branch, MCH Project #:UH7MC30774-01-00 http://mchb.hrsa.gov