Health Library

TANGO2-Related Disorder in Children

Doctors may also call it:

• TANGO2 deficiency disorder
• TANGO2-related metabolic encephalopathy and arrhythmias
• TANGO2-related metabolic crisis and arrhythmia syndrome

These are different names for the same condition.

Children with this condition are born with changes in the TANGO2 gene. This gene normally helps cells process fat for energy. When cells cannot use fat the usual way, the effects can reach many parts of the body. This includes the nervous system, muscles, heart and thyroid gland. It can also affect a child's overall growth and development.

Symptoms vary a great deal from child to child. Some children have mild, ongoing symptoms, like developmental delay or clumsiness. Other children also have sudden, serious medical crises—such as a dangerous drop in blood sugar or a life-threatening heart rhythm problem—that need emergency treatment. Early diagnosis and a strong prevention plan can lower how often these crises happen and how severe they are. This helps lower the chance of a life-threatening emergency.

TANGO2 can affect many parts of the body at once. Because of this, children do best with a care team that knows rare metabolic, neurologic and heart conditions well.

What Causes TANGO2-Related Disorder?

TANGO2-related disorder is caused by changes in the TANGO2 gene, known as pathogenic variants. These are gene changes that stop a gene from working the way it should. The TANGO2 gene carries instructions for a protein that helps cells manage fat and energy. Like with all genes, a child has two copies of TANGO2—one inherited from each parent. When both copies of the gene are affected, the protein does not work the way it should. A single changed copy does not cause symptoms on its own.

Parents who carry only one changed copy are called carriers. Carriers are usually healthy. They do not have symptoms themselves.

When both parents are carriers, each pregnancy carries a chance that the child will inherit two changed copies. This is called the recurrence risk. For two parents who are both carriers, each pregnancy has about a 1 in 4 (25%) chance of the child having TANGO2-related disorder. A genetic counselor can explain this risk in detail. They can also talk through options for future pregnancies.

Genetic counseling can help the whole family. Parents, siblings and other relatives can learn their own chance of carrying a changed gene. Siblings may need genetic testing even if they seem healthy. Mild or early symptoms are not always easy to spot.

Signs and Symptoms Parents May Notice

Symptoms often begin in infancy or early childhood. They most commonly appear as developmental delay in the first few years of life. TANGO2-related disorder is a lifelong condition. Some people are not diagnosed until later in life if their childhood symptoms were mild or went unrecognized.

Symptoms and their severity vary widely from child to child. Not every child has every symptom. Developmental delay and many of these symptoms can also happen with other childhood conditions. On their own, they don’t confirm TANGO2-related disorder. Doctors look at the whole pattern of symptoms together, along with genetic testing, to make the diagnosis.

Common signs and symptoms include:

• Developmental delay: Reaching milestones like sitting, walking or talking later than expected.
• Speech delay or difficulty: Trouble forming words clearly or building vocabulary at the usual pace.
• Intellectual disability: Challenges with learning and problem-solving. This can range from mild to more significant.
• Poor coordination or unsteady walking (ataxia): This can make a child look clumsy or off-balance.
• Sudden episodes: Short bursts of weakness, clumsiness, drooling, slurred speech or confusion. Families sometimes call these TANGO2 spells.
• Seizures: Sudden bursts of abnormal electrical activity in the brain. This might look like shaking or jerking movements, a blank stare with no response, or a brief loss of awareness.
• Movement disorder: Abnormal involuntary movements can include shaking (tremor), abnormal postures (dystonia), and increased muscle tone (spastic and/or dystonic hypertonia). Movement disorder symptoms can be persistent and/or can come and go.
• Hypothyroidism: An underactive thyroid gland. This can cause tiredness, weight gain, constipation, dry skin or slower-than-expected growth.
• Constipation: Infrequent, difficult or uncomfortable pooping.
• Eye alignment concerns: Such as exotropia, when one or both eyes turn outward instead of lining up together.
• Hearing concerns: Some children develop difficulty hearing over time. This usually develops as a child grows, rather than being one of the first signs doctors see at diagnosis.

Doctors tailor monitoring and treatment to each child's specific pattern of symptoms.

How Is TANGO2-Related Disorder Diagnosed?

Doctors usually start by reviewing a child's symptoms and medical history. They look closely for a pattern. A pattern is when several of these signs show up together in the same child, rather than just one symptom on its own. This can include developmental delay, an unexplained episode of muscle breakdown (rhabdomyolysis, with muscle pain, weakness or dark pee), an abnormal heart rhythm (arrhythmia), or a metabolic crisis like the ones described below.

Doctors often recommend genetic testing after an unexplained metabolic crisis, an episode of rhabdomyolysis, an arrhythmia, or developmental concerns without another clear cause. Genetic testing looks for pathogenic variants in the TANGO2 gene. It is often done through a broad test called whole exome sequencing, which reads many genes at once. This test confirms the diagnosis.

During an episode, doctors also order lab tests, or blood tests. These help show what is happening in the body right now. They are used to manage a crisis while it is happening; they are not needed to make the diagnosis. Genetic testing can confirm TANGO2-related disorder at any time, even if a child has never had a metabolic crisis. Tests can include:

• Blood glucose, to check for low blood sugar
• Creatine kinase (CK), a marker of muscle breakdown
• Liver enzymes
• Electrolyte panel, which also assesses kidney function
• Cardiac markers, when heart involvement is suspected

Heart testing is also part of the diagnostic picture. This can include an EKG, a Holter monitor or an echocardiogram. Doctors typically recommend baseline heart testing for every child diagnosed with TANGO2-related disorder, even if they have no heart symptoms. This is because heart rhythm problems are not always noticeable and can develop without warning.

TANGO2-related disorder affects many body systems. Because of this, diagnosis often draws on genetics, metabolism, neurology and cardiology specialists working together.

TANGO2 Spells vs. Metabolic Crises

Families often use the term "TANGO2 spell." This means a sudden, temporary worsening of a child's usual symptoms. A spell may include loss of balance, a head or body tilt, drooling, tiredness, more trouble speaking than usual or brief confusion. Spells are usually not life-threatening. They can still be frightening to watch.

Both TANGO2 spells and metabolic crises are usually set off by physical stress on the body, such as illness, fasting, dehydration, overheating or intense exercise (see “What Can Trigger a Metabolic Crisis?” below). Most children with TANGO2-related disorder have spells at some point, but how often and how severe they are varies widely from child to child.

A metabolic crisis is more serious than a TANGO2 spell. During a crisis, the body's ability to manage energy breaks down further and can lead to:

• Rhabdomyolysis (rapid breakdown of muscle tissue), which can cause muscle pain, weakness and dark, tea-colored pee. Rhabdomyolysis can develop quickly, sometimes within hours to a day once a crisis begins.
• Low blood sugar, which can cause shakiness, sweating, confusion or unusual sleepiness.
• Changes in liver enzymes, which are usually found only through blood tests and may not cause any symptoms a parent can see.
• Dangerous heart rhythm problems, which can cause a racing or irregular heartbeat, fainting or chest discomfort.

A metabolic crisis needs quick medical care.

Some signs of a metabolic crisis are easy for a parent to notice, such as muscle pain, dark tea-colored pee, unusual sleepiness or a racing heartbeat. Others, like changes in liver enzymes, can only be found with blood tests. This is why any illness combined with poor eating, unusual tiredness or muscle pain should be checked by a doctor right away, even if a parent cannot see every warning sign.

Spells and crises can look similar at first. Because of this, it’s helpful for families to have a clear action plan. This plan should be built with the child's medical team. It should spell out which symptoms call for home monitoring and which call for emergency care. Any symptoms that are severe, unusual or happen along with illness or poor eating should be checked right away.

Cardiac Risks and Heart Rhythm Problems

TANGO2-related disorder can affect the heart's electrical system. Heart cells use electrical signals to tell the heart when to beat. The energy problems caused by TANGO2-related disorder can disrupt these signals. This can lead to serious arrhythmias, or abnormal heart rhythms.

An EKG records the heart's electrical activity. Many children with this condition show a prolonged QTc interval on this test. This means the heart takes longer than usual to reset between beats. A prolonged QTc raises the risk of ventricular tachycardia, a fast and abnormal rhythm from the heart's lower chambers. It also raises the risk of torsades de pointes, a specific and dangerous type of ventricular tachycardia.

Some children also develop cardiomyopathy, a disease of the heart muscle that can weaken the heart's pumping ability.

Left untreated, these heart rhythm problems can cause fainting, cardiac arrest (heart stops beating) or sudden death. Cardiomyopathy can also worsen over time and lead to heart failure, when the heart cannot pump enough blood for the body’s needs. Regular heart monitoring helps doctors catch these problems early, often before a child has any symptoms.

Metabolic stress (the strain the body feels during illness, fasting or dehydration) can raise these cardiac risks. This is one reason prevention matters so much.

Pediatric cardiology and electrophysiology (heart rhythm specialists) play a central role in TANGO2 care. Children may need regular EKGs, Holter monitors (heart monitor worn for a day or more) or echocardiograms (ultrasound of the heart) to track heart rhythm and function over time, even when a child feels well. Testing is done on a schedule set by their cardiologist, often every few months to once a year. It depends on how severe their condition is and whether they’ve had a crisis in the past.

What Can Trigger a Metabolic Crisis?

Metabolic crises are usually set off by physical stress on the body. Common crisis triggers include:

Illness or fever

• Vomiting or diarrhea
• Eating or drinking less than usual—even without going without food entirely, reduced intake can strain the body's limited energy reserves
• Prolonged fasting—going an extended time without any food at all
• Dehydration—not having enough fluid in the body, which can result from reduced drinking, vomiting, diarrhea or heat exposure
• Surgery or procedures that require fasting first
• Heavy physical exertion, such as intense exercise or competitive sports
• Heat exposure or other physical stress on the body

Because heavy exertion is a known trigger, children with TANGO2-related disorder should only take part in intense exercise or competitive sports with guidance from their cardiology and neurology team, who can help decide what level of activity is safe for the child.

Children with TANGO2-related disorder cannot use fat for energy the way other children can. Because of this, their bodies are especially vulnerable when energy needs go up or food intake goes down.

Prevention of a metabolic crisis focuses on three things:

• Eating regular meals and snacks to avoid catabolism (the body breaking down its own tissue for fuel)
• Encouraging fluids, to avoid dehydration
• Not skipping meals, especially during illness, to avoid prolonged fasting

Every child's care team should help build a written illness plan. This plan should explain what to do at the first sign of illness. It should also explain how long a child can safely go without eating and when to go to the emergency room.

Emergency Care for TANGO2 Metabolic Crisis

Families should carrying a written emergency letter, or protocol. This is a one- or two-page summary, prepared with the care team. It explains the condition to any doctor or emergency team who may not know it well.

Families typically keep a copy on hand at all times. This can mean a printed page in a bag or glove compartment, plus a photo of the letter saved on a phone. Copies are often shared with the child's school nurse and pediatrician, too.

Emergency care may be needed when a child has:

• Illness with poor eating or drinking
• Vomiting
• Signs of dehydration, such as a dry mouth, few or no tears, less peeing than usual or unusual sleepiness
• Weakness, confusion or unusual tiredness
• Muscle pain or dark, tea-colored pee—both can be signs of rhabdomyolysis, or muscle breakdown
• Fainting, a racing heartbeat or other signs of an abnormal heart rhythm, such as a fluttering feeling in the chest or an irregular pulse

Quick treatment with IV glucose-containing fluids can help prevent or reverse a metabolic crisis, when directed by the care team. During a crisis, doctors watch closely for rhabdomyolysis, low blood sugar, electrolyte imbalances and arrhythmias.

Some children need care in the intensive care unit (ICU). This is more likely if a child looks seriously ill or has concerning lab results or EKG findings. TANGO2-related disorder is rare. Because of this, emergency teams often need quick, disorder-specific guidance from the child's regular specialists.

Specialists Involved in TANGO2 Care

TANGO2-related disorder can affect many parts of the body. Because of this, children often see a team of specialists, which may include the following areas:

• Genetics: Confirms the diagnosis and guides family testing and counseling
• Metabolism: Manages the underlying energy-processing problem and crisis prevention
• Neurology: Manages seizures, abnormal movement and developmental concerns
• Cardiology and electrophysiology: Monitors heart rhythm and heart muscle function
• Endocrinology: Manages thyroid function
• Gastroenterology or nutrition: Supports feeding, digestion and nutrition planning
• Ophthalmology: Monitors eye alignment and vision
• Audiology: Monitors hearing
• Physical, occupational and speech therapy: Supports movement, daily skills and communication
• Social work and care coordination: Helps families manage appointments, resources and school planning

Rare, multisystem conditions like TANGO2-related disorder often benefit from the resources at a children's hospital. Specialists across these fields can work together on one care plan.

Ongoing Treatment and Daily Management

There is no cure for TANGO2-related disorder. Treatment focuses on preventing crises and managing symptoms day to day. A child's care team may recommend:

• A daily multivitamin or B-complex vitamin, at a dose the care team sets. Research suggests this may lower the chance of a metabolic crisis. Scientists are still studying exactly how it helps.
• Avoiding prolonged fasting
• Illness and sick-day nutrition planning, so families know how to keep a child's energy intake up when they are sick
• Support with hydration, especially during illness or hot weather
• Seizure treatment, if a child has seizures
• Medications to minimize abnormal movement disorder(s)
• Thyroid hormone replacement, if a child has hypothyroidism
• Feeding therapy or nutrition support, if needed
• Orthopaedic assessment of joint and spine health
• Developmental therapies, including physical, occupational and speech therapy
• Assessing the need for medical devices (orthotics, communication device, wheelchair)
• School and developmental support to help a child learn and grow

Nutrition and Fasting Prevention

Children with TANGO2-related disorder cannot rely on fat for energy the way other children can. Because of this, regular meals and snacks are an important part of daily care. Some children benefit from a bedtime snack. This helps avoid going too many hours without food overnight.

Hydration matters especially during illness or hot weather. The body loses fluids faster at these times.

Restrictive diets should be avoided unless a doctor specifically prescribes and supervises them. This includes ketogenic diets, which shift the body toward burning fat on purpose. These diets can raise crisis risk in this condition.

Families often need to plan ahead for school days, travel or sports. They also need to plan ahead for medical procedures that require fasting. If a child cannot eat or drink normally for any reason, the family's illness plan should explain what to do and when to call the care team. Nutrition, metabolism and primary care teams usually coordinate this planning together.

School, Activity and Family Life

Children with TANGO2-related disorder often benefit from learning support at school. This may include an individualized education plan (IEP) or classroom accommodations. Fatigue and stamina can vary from day to day. Activity levels may need to change based on how a child feels.

Safety planning matters for children who have seizures or cardiac symptoms. An illness action plan should be shared with school nurses. This helps staff know what to watch for and who to call. Cardiology and neurology can offer guidance on which activities are safe for each child. For example, contact sports, intense exercise or activities with a high risk of overheating may need extra precautions, or may need to be avoided.

Teachers, coaches and other caregivers should have basic emergency information on hand, such as a copy of the child’s emergency letter, a list of warning signs to watch for, and phone numbers for parents and the care team.

Caring for a child with a rare, complex condition can be hard for the whole family. Support for siblings and caregivers—such as support groups, counseling or respite care—is an important part of overall care.

What Is the Long-Term Outlook for Children With TANGO2?

Outcomes for children with TANGO2-related disorder vary widely. They depend on how often and how severe metabolic crises are, and how early the condition is diagnosed. Each metabolic crisis carries some risk of affecting the brain, heart or muscles. Dangerous heart rhythms during a crisis are the most life-threatening risk. Preventing crises through early diagnosis and a solid prevention plan can make a difference in a child's long-term health and development.

Ongoing monitoring is a lifelong part of care. Children are typically followed for heart rhythm, thyroid function, seizures, development, nutrition, vision and hearing. Specialists set a regular schedule for this monitoring.

As children with TANGO2-related disorder grow into adults, their care team helps plan the move to adult specialists. This keeps the same kind of coordinated multisystem care going.

TANGO2-related disorder is rare. Researchers are still learning about its natural history and the best ways to treat it. Research studies and patient registries play an important role in improving future care. A patient registry is a secure database that tracks health information from many patients with the same rare condition over time, helping researchers spot patterns and test new treatments. A child’s genetics or metabolism care team often tells families about available registries, sometimes around the time of diagnosis and sometimes later on. Families may be offered the chance to take part, and joining is always voluntary.

Why Choose a Children's Hospital for TANGO2 Care?

Children with TANGO2-related disorder can be cared for by a general pediatrician working alongside community specialists. But coordinating genetics, cardiology, neurology, metabolism and other services across separate offices can be difficult for a condition this rare and complex.

Rare genetic and metabolic disorders like TANGO2-related disorder call for coordinated, experienced care. A children's hospital can offer:

• Experience diagnosing and managing rare genetic and metabolic disorders
• Rapid access to pediatric cardiology and electrophysiology for heart rhythm concerns
• Coordinated emergency planning for metabolic crises
• Pediatric genetics services and metabolic testing
• Neurology support for seizures, development and movement symptoms
• Pediatric intensive care access for metabolic or cardiac emergencies
• Nutrition and feeding support built for metabolic conditions
• Therapy services and school support coordination
• Care coordination that connects every specialist involved in a child's complex, multisystem condition

Frequently Asked Questions

Is TANGO2 the same as TANGO2 deficiency disorder?

Yes. TANGO2, TANGO2 deficiency disorder and TANGO2-related metabolic encephalopathy and arrhythmias are different names for the same condition.

How is TANGO2 inherited?

It is passed down in an autosomal recessive pattern. A child needs two changed copies of the gene, one from each parent, to be affected. A single changed copy makes a person a healthy carrier. When both parents are carriers, each pregnancy has about a 1 in 4 chance of the child being affected.

What is a TANGO2 spell?

It is a sudden, usually temporary worsening of a child's baseline symptoms, such as loss of balance, drooling or trouble speaking.

What is a TANGO2 metabolic crisis?

It is a more serious medical event that can involve muscle breakdown, low blood sugar, liver changes or dangerous heart rhythm problems. It needs prompt medical care, since delays can allow these problems to become more severe or life-threatening.

Why can TANGO2 cause rhabdomyolysis?

The body cannot process fat for energy normally. Physical stress can then cause muscle tissue to break down rapidly, called rhabdomyolysis.

Why can TANGO2 cause dangerous heart rhythms?

TANGO2 can affect the heart's electrical system. This can prolong the QTc interval and raise the risk of serious arrhythmias. Left untreated, these problems can lead to fainting, cardiac arrest or sudden death, which is why regular heart monitoring matters.

What triggers a TANGO2 metabolic crisis?

Illness, fasting, dehydration, vomiting, heavy exertion and heat exposure are common triggers.

How is TANGO2 diagnosed?

Doctors combine a review of symptoms and medical history with genetic testing to confirm the diagnosis.

Can genetic testing confirm TANGO2?

Yes. Genetic testing that finds pathogenic variants in both copies of the TANGO2 gene confirms the diagnosis.

What should be in a TANGO2 emergency letter?

It should explain the condition, list warning signs and outline the treatment steps an emergency team should follow, as set by the child's care team.

What should families do during illness or poor eating?

Follow the child's written illness plan. Focus on keeping fluids and calories up. Contact the care team right away if a child cannot eat or drink normally.

Are B vitamins used for TANGO2?

Yes. Many care teams recommend a daily multivitamin or B-complex vitamin. Research suggests it may help lower the chance of a metabolic crisis.

Can children with TANGO2 go to school?

Yes. Many children attend school with support, such as an individualized education plan and a shared illness action plan for staff.

Can children with TANGO2 play sports?

Some children can be active with guidance from their cardiology and neurology team. These specialists help decide which activities are safe. Because intense exercise is a known trigger for a metabolic crisis, this guidance matters even for children who feel well.

Do siblings need genetic testing?

Siblings may need genetic testing even if they seem healthy. Mild or early symptoms are not always easy to spot.

What specialists treat TANGO2?

Care often involves genetics, metabolism, neurology, cardiology, endocrinology, gastroenterology, ophthalmology, audiology and therapy specialists working together.