Información general sobre la enfermedad
- Morquio syndrome
- Morquio-Brailsford syndrome
- MPS IVA
Tipo de enfermedad
Prevalencia al nacimiento
It is unknown how many babies are born with this rare condition each year in the United States.
Resultado del examen
Qué es Mucopolysaccharidosis Type IVA
Mucopolysaccharidosis type IVA (MPS IVA) is one condition in a group of inherited (genetic) conditions that prevent the body from processing sugars properly.
The body uses complicated sugars called glycosaminoglycans (GAGs) in several important processes. An enzyme called N-acetyl-galactosamine-6-sulfatase (GALNS) breaks down GAGs so that the body can use them. This process occurs in special compartments inside your cells called lysosomes.
MPS IVA is a condition that occurs when GALNS is absent, or present at low levels. The lysosomes then have trouble breaking down GAGs. This causes a buildup of GAGs in the tissues that can result in problems throughout the body. GAGs used to be called mucopolysaccharides, which is where the condition got its name.
High levels of GAGs can damage many parts of the body. This damage leads to the signs and symptoms of the condition.
Examen de recién nacidos y seguimiento
Newborn screening for MPS IVA is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
During screening, a special machine measures the activity of the enzyme GALNS in your baby’s blood. Screening may also measure GAGs levels. Babies with absent or low activity levels of GALNS and high levels of GAGs may have MPS IVA.
If your baby’s blood spot screening result for MPS IVA is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood and/or urine tests
- Genetic testing using a blood sample
You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition may happen.
Detalles de la enfermedad
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.
The timing and type of problems caused by MPS IVA vary between people depending on whether they have a severe form of the disease right away or a later-onset of the disease. For the severe form of the condition, outward signs are usually seen between one and three years. For the milder form, signs or symptoms may not appear under later in childhood.
Signs of the condition may include the following:
- Soft out-pouching around their belly button or lower stomach (umbilical or inguinal hernia)
- Prominent forehead
- Loose and very flexible joints (hypermobility)
- Skeletal problems (including, rounding of the upper back/curved spine)
- Facial features that are different from their parents
- Cloudy eyes
- Frequent ear and respiratory infections
- Hearing loss
- Sleep problems
- Teeth problems
The condition is caused by a change in the GALNS gene. This gene gives your body instructions for making the GALNS enzyme to break down the complex sugars called GAGs. Unlike some other sugars, you produce GAGs rather than consume them from food.
When the GALNS gene is changed, your baby’s body cannot properly break down these substances. They build up in cells throughout the body.
- MPS IVA is an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking GALNS gene to their baby. Only babies with two nonworking GALNS genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the GALNS gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the GALNS gene, they have a 1 in 4 chance of having a child with MPS IVA.
- Carriers for MPS IVA often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with MPS IVA.
- Parents who already have a child with MPS IVA still have a 1 in 4 chance of having another child with MPS IVA. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Tratamiento y manejo
It is important to talk to your health care provider about what type of evaluations may be useful to look for problems and which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.
Testing may include:
- MRI or CT scans
- Ultrasound picture of the heart (echocardiogram)
- Test of the heart’s electrical signals (electrocardiogram, ECG or EKG)
- Hearing tests
Treatments may include the following:
- Enzyme replacement therapy (ERT)
- Physical therapy
Health outcomes for MPS IVA vary based on a child’s form of the condition. For children with the less severe form, early and ongoing treatment can lead to healthy growth and development. For children with the more severe form, early treatment can prevent or delay some serious symptoms of the condition.