Newborn Screening

Contact Info

Newborn Screening Program

651-201-5466

800-664-7772 (toll-free)

health.newbornscreening@state.mn.us

New Condition Information

MDH began screening for Duchenne muscular dystrophy (DMD) and guanidinoacetate methyltransferase (GAMT) deficiency on Monday, February 24, 2025.

With the addition of these two conditions, we expect about 300 infants per year to require additional testing and about 6-10 of these infants to be diagnosed with DMD or GAMT deficiency. Based on what we’ve heard from other states, we expect the NICU population will see an increase in the number of positives/rescreens for both DMD and GAMT deficiency.

Please note, to reduce the number of unnecessary diagnostic testing and referrals for DMD, if the initial newborn screen shows an elevated level of CK-MM (an analyte used to measure skeletal muscle damage), our genetic counselors will be contacting providers to order a second newborn screen to be collected AFTER 2 weeks of age to allow time for elevations in CK-MM to normalize after the birthing process.

Based on what we’ve heard from other states, you will be seeing an increase in repeat specimens requested from us and will likely also see an increase in your outpatient lab orders.If you have any questions or concerns or need additional screening cards earlier than your regular shipment, please contact our Newborn Screening Operations unit: 651-201-5466 or 800-664-7772 (toll-free) or health.newbornscreening@state.mn.us.

Duchenne muscular dystrophy (DMD)

Duchenne muscular dystrophy (DMD) is an x-linked condition caused by mutations of the dystrophin gene. Dystrophin is a protein that protects muscle cells from damage. Without it, muscle breaks down.

Blood Spot Disorders - Other Disorders

When muscles are damaged and breakdown, creatine-kinase (CK-MM) leaks into the blood stream. The higher the levels of CK-MM in the blood, the more muscle damage has occurred. People with Duchenne muscular dystrophy (DMD) have a mutation in their dystrophin gene, which creates a protein that protects muscle cells from damage. Without it, muscle tissues fail to regenerate and are replaced by scar tissues and fat. This leads to extreme muscle fragility and weakness as the individual ages.

DMD is a progressive muscle disorder with noticeable symptoms generally appearing between two and three years of age, starting with difficulty moving, walking, and running. Other common symptoms in childhood are large calf muscles paired with thin thighs (pseudohypertrophy), and slight learning disabilities. As DMD progresses, additional health issues may arise:

Children with DMD usually lose the ability to walk and use a wheelchair by age twelve.
By their early twenties, individuals with DMD often develop weak hearts (cardiomyopathy).
Heart and respiratory problems worsen with age, and eventually result in death when the individual is in their 30’s.

There is no cure for Duchenne muscular dystrophy, but treatment can help slow the disease and improve quality of life. Management may include:

Medication taken by mouth (oral glucocorticoid treatment)
New gene therapies may be available that replace or partially repair the body’s instructions for making the specific muscle protein (dystrophin) (like exon-skipping and gene replacement therapies)
Screenings to find heart and muscle issues early
Tailored physical therapy

For Family: Elevated CK-MM (Borderline Result) (PDF)

For Family: Persistently Elevated CK-MM: Risk for Duchenne Muscular Dystrophy (PDF)

For Providers: Elevated CK-MM (Borderline Result) (PDF)

For Providers: Persistently Elevated CK-MM (PDF)

Specialist Resources: Duchenne Muscular Dystrophy (PDF)

Newborn screening for Duchenne muscular dystrophy

Duchene muscular dystrophy (DMD) is caused by a mutation causing muscle breakdown and primarily affects boys with an onset of symptoms around 2-3 years of age. Muscle weakness is first noticed in legs and arms, eventually leading to loss of mobility and weakness of internal muscles needed for breathing. Symptoms of DMD, if not identified in the newborn period, can go unrecognized for years. On average, DMD is not diagnosed until the age of 5, at which point muscle may already be severely damaged.

Additional information including a clinical summary and treatment options is available Blood Spot Disorders: Other Disorders

In Minnesota, we expect the analyte used to screen for this condition to be elevated in approximately 300 infants. These infants will require a second screen to better assess their risk. We anticipate 6-10 confirmed cases of DMD each year.

Screening will measure the CK-MM (creatine kinase muscle-muscle isoenzyme, creatine kinase that is specific to skeletal muscle) levels in dried blood spots. This analyte is elevated when muscle is damaged, including injury obtained from the normal birthing process, but it will also be elevated from muscular disorders such as DMD and limb girdle muscular dystrophy.

Newborn screening is not diagnostic for DMD or any other muscular condition. Screening is meant to identify babies who are most likely to benefit from further testing.

After an initial screen shows an elevation in CK-MM, a second newborn screen should be collected AFTER 2 weeks of age to allow CK-MM to normalize after the birthing process. Please check with your clinic’s lab to see how to order a newborn screen (sometimes called a newborn metabolic screen). Every clinic should have newborn screening filter paper cards on hand, if they do not have these or are not set up to send in samples, they can contact our Newborn Screening Operations unit: 651-201-5466 or 800-664-7772 (toll-free) or health.newbornscreening@state.mn.us.

Providers can reassure families that most of the time these levels normalize. Waiting to collect the second screen until after two weeks of age makes the screen more reliable, so it’s best to wait. After a second screen shows an elevation in CK-MM, a referral to a neuromuscular specialist is recommended. They will coordinate the appropriate testing to find out if baby has a condition like DMD or not. Contact information for these specialists can be found on MDH’s website Specialist Resources: Duchenne Muscular Dystrophy.

CK-MM may be elevated in infants due to muscle trauma that may be the result of complicated deliveries including breech presentation, shoulder dystocia, resuscitation, or the use of forceps and/or vacuum.

For some of the NICU infants under your care, their second screen (drawn after two weeks of age) may be collected in the NICU. This will allow time for elevations to normalize after the birthing process. This timing aligns nicely with the low birthweight protocol, but you may still see an increase in the number of rescreen requests you receive from us. If you receive a request for a second newborn screen due to elevated CK-MM and the infant will be discharged before two weeks of age, please ensure the recommendation for a repeat is included in the discharge summary.

If the provider/family has clinical or family history concerns, please pursue further evaluation, even if the newborn screen was normal. It is important to note that infants who are extremely low birthweight may be more likely to be missed with screening due to decreased muscle mass.

Results and recommended next-steps will depend on the specimen timing and if it’s the first or second screen with elevated CK-MM.

DMD will appear as a new line on the newborn screening report.

Guanidinoacetate Methyltransferase (GAMT) deficiency

GAMT deficiency is a genetic disease where the body doesn’t produce enough creatine, which is important for storing and using energy. GAMT deficiency affects many organs, but especially the brain and muscles. Early treatment can prevent and reduce symptoms associated with GAMT deficiency.

Blood Spot Disorders - Metabolic Disorders, Amino Acid Profile.

GAMT is an enzyme that normally helps break down GUAC into creatine. Creatine is used by our brain and muscles to store and use energy. People with GAMT deficiency have a mutation in the GAMT gene, so that it doesn’t work properly. Without GAMT, creatine levels are lowered and GUAC builds up. GUAC is toxic in large quantities and can cause damage to the nervous system. Creatine deficiency is associated with brain and muscle issues.

Symptoms typically start before age one but can begin as late as age three. Early findings are often non-specific. Hypotonia and delays in infant milestones like sitting, crawling, walking, and speaking are typically noticed first. If untreated, most children develop intellectual disability, behavioral disorders, and epileptic seizures. Poor growth and abnormal uncontrolled movements (such as tremors or tics) may also occur.

There is no cure for Guanidinoacetate Methyltransferase (GAMT) deficiency, but early treatment can prevent and reduce symptoms. Treatment may include:

Medication taken by mouth (creatine, ornithine, sodium benzoate)
Special diet low in protein
Screenings to find heart and muscle issues early
Speech, occupational, and behavior therapy

For Family: Elevated GUAC: Risk for GAMT Deficiency (PDF)

For Providers: Elevated Guanidinoacetate GUAC (PDF)

Specialist Resources: Metabolic Specialists (PDF)

Newborn screening for GAMT deficiency

Guanidinoacetate methyltransferase (GAMT) deficiency is a lifelong metabolic disorder causing a toxic buildup that results in serious brain and muscle problems if left untreated. GAMT deficiency symptoms typically begin before the age of 1 and as late as 3 years. These symptoms include late sitting, walking, speaking, and growth. If untreated, most children develop learning and behavioral challenges. GAMT deficiency has an expected incidence of 1 in 250,000-500,000. Based on Minnesota’s birthrate, we expect to identify 0-1 infants with GAMT deficiency per year. Borderline screens are not expected.

Additional information including a clinical summary and treatment options is available Blood Spot Disorders: Metabolic Disorders, Amino Acid Profile

Analytes used to screen for GAMT deficiency include guanidine acetate (GUAC) and creatine (CRE). Specimens with elevated GUAC and GUAC*1000/CRE ratio will be reported as positive with a recommendation of referral to a metabolic specialist. Specimens with elevated GUAC but normal ratio in an infant weighing >2000 grams will be sent to Mayo Clinic Laboratories for further testing. See ‘Special Considerations’ below for approach taken with infants weighing ≤2000 grams.

As always with newborn screening specimens from the NICU, please do not draw the specimen from a line, if possible, and avoid contaminating the specimen or card with TPN. False positive results have been reported in NICU patients which may be attributed to complex clinical course, transfusions, or other complicating factors. Positive screens in infants weighing less than 2000 grams will follow the established low birthweight protocol. Additional screens collected at 14 and 30 days or at discharge will provide a better risk assessment for GAMT deficiency. A genetic counselor from MDH’s Newborn Screening Program will notify the care team when a referral to a specialist is needed.

GAMT will be added to the Amino Acid Profile on the newborn screening report and will not be its own line in the testing result grid. The only change is that asterisks will be added to “Acylcarnitine Profile” and “Amino Acid Profile” so it will look like “Acylcarnitine Profile**” and “Amino Acid Profile**” on every report. The asterisks designate the test as a lab developed test.

Additional information

Newborn Screening Fact Sheet (PDF)

Newborn Screening Infographic (PDF)

Newborn Screening for Duchenne Muscular Dystrophy (DMD) and Guanidinoacetate Methyltransferase (GAMT) Deficiency has Begun (PDF)

Filling out newborn screening card

Accurate completion of newborn screening cards helps our staff locate infants with abnormal results quickly and facilitates timely follow-up testing. If affected infants do not receive timely follow-up care, many of the disorders can lead to permanent mental or physical problems or even death. The submitter is legally responsible for the accuracy and completeness of the information on the newborn screening card. Please take special care to fill out all fields.

Newborn Screening Information for Providers: Screening Card Instructions (PDF)

Newborn Screening Information for Providers: Screening Card Tips (PDF)