Hypotonia ataxia and delayed development syndrome (HADDS)

What is hypotonia, ataxia, and delayed development syndrome (HADDS)?

HADDS is a neurological (brain and nervous system) condition that affects a range of physical features and abilities. Children with HADDS are born with differences in their brain that affect how their bodies develop and work.

Children with HADDS may need special care throughout their lives.

• Some require help with daily activities, such as dressing and mobility.

• Some may require medicine or procedures to help them pee and poop, because certain muscles in their bladder and bowel don’t work properly. Helping them pee is especially important because if urine backs up into their kidneys (called hydronephrosis), it can cause infection and damage.

How is hypotonia, ataxia, and delayed development syndrome (HADDS) different from other syndromes?

HADDS can appear similar to other conditions, such as spina bifida, but many aspects make it distinct, such as:

• Lower spine - Imaging tests usually show nothing unusual about the lower spines of children with HADDS. In contrast, children with spina bifida have structural differences in the lower part of their spines.

• Bladder issues - Children with HADDS often have swollen bladders and difficulty urinating (peeing). However, children with spina bifida tend to develop small bladders and urinate frequently.

What are the signs and symptoms of hypotonia, ataxia, and delayed development syndrome (HADDS)?

Signs and symptoms that can occur with HADDS include:

• Low muscle tone (hypotonia)

• Poor muscle control (ataxia)

• Delays in motor, speech and/or cognitive (thinking) skills

• Little or no response to pain

• Vision problems

• Misaligned eyes or strabismus

HADDS may also lead to urinary and bowel problems such as:

• Urinary tract infections (UTIs)

• Vesicoureteral reflux (VUR)

• Difficulty having bowel movements or constipation

How is hypotonia, ataxia, and delayed development syndrome (HADDS) diagnosed?

First, your child’s doctor will perform a physical exam and talk to you about their symptoms and health history. The exam may include having your child walk across the room and do other movements so the doctor can evaluate their muscles and flexibility. Your doctor may order tests to get more information and rule out other conditions.

These tests may include:

• Blood tests are an important way to see how well the kidneys, liver and other organs are functioning.

• Magnetic resonance imaging (MRI) - An MRI is an imaging test that uses magnetic fields and radio waves to create pictures of the inside of the body. For HADDS, our specialists use MRI to evaluate a child’s spine and rule out other conditions.

• Genetic testing - Our team can confirm a diagnosis of HADDs using genetic testing. To do the test, we’ll take a small sample of your child’s blood and send it to a lab. Our genetic specialists and lab use the latest technology to get fast, accurate results. We also have genetic counselors and social workers who can help you and your child make health care decisions based on the diagnosis.

What causes hypotonia, ataxia, and delayed development syndrome (HADDS)?

HADDS results from a mutation (change) in a gene called EBF3. It’s unclear what causes these gene mutations, and the changes can cause symptoms ranging from mild to severe.

The mutation affects how a child’s brain and body develop in the womb. One example is the sphincter muscles that open and close to let pee and poop out of the body. With HADDS, the sphincters are extra tight and don’t open easily. As a result, it’s harder for children to pee and poop, and they may need treatment to help.

How is hypotonia, ataxia, and delayed development syndrome (HADDS) treated?

Treatment for HADDS varies depending on the symptoms and needs of each child. Although HADDS is a lifelong condition, early diagnosis and treatment can make a big difference in a child’s life. The right care from the start can greatly improve a child’s mental and mobility skills and help them avoid serious challenges of this condition. Building their skills and abilities when a child is young can help them manage their condition better in the future.

A child may receive care from multiple specialists, including:

• Neurologist - These doctors diagnose and treat conditions affecting the brain, spinal cord and nerves. Our neurologists provide overall care for children who have HADDS, including tests to monitor the brain and spine.

• Urologist - Urologists diagnose and treat conditions that affect the bladder, kidneys and other parts of the urinary tract. For HADDS, our urologists may recommend treatment to help children pee. Treatment may involve medication, a catheter (plastic tube) to drain urine from the bladder into a bag outside the body, or a procedure that lets the bladder empty urine through a hole in the abdomen (vesicostomy).

• Physiatrist - These doctors diagnose and treat conditions affecting the bones, joints and muscles. Children with HADDS often have tight leg muscles, so a physiatrist may recommend physical therapy or injections to help loosen them.

• Gastroenterologist - A gastroenterologist is a doctor who provides care for conditions affecting the digestive system, including the intestines. These experts can help children with HADDS who have trouble pooping. Treatment may include injections to relax muscles in the anus (end of the large intestine where poop exits the body).

• Occupational therapist - These specialists focus on the movements and tasks that are part of daily life, such as getting dressed and grasping toys and other objects. Our occupational therapists may provide exercises and lessons that help children with HADDS perform these tasks.

• Ophthalmologist - Ophthalmologists are doctors who diagnose eye diseases and provide medical and surgical treatment. Children with HADDS who have vision problems may receive testing or treatment from an ophthalmologist.