Newborn screening for Duchenne muscular dystrophy

Guest blog by Kathi Kinnett RN/CNP
 

Currently there is no newborn screening for Duchenne in the United States. However, groundbreaking work from Jerry Mendell’s lab at The Ohio State University may have a hand in changing this.
 

Mendell’s recent pilot study was funded by the Centers for Disease Control (CDC) and was performed in Columbus and Cincinnati, Ohio. Mendell utilized dried blood spots from a single infant heel stick obtained 24-48 hours after birth, now used for newborn screening for other conditions, to develop a 2-step screening process for Duchenne. First, the blood was tested for creatinine kinase (CK), the enzyme released from muscle when it is damaged. (A high CK is generally the first indicator that the child may have Duchenne, and has been thought to always be high in the newborn period due to the trauma of birth.) Mendell found that, even if CKs were slightly elevated, very few infants had CKs elevated above 750 U/L. Second, those few with CKs above 750 U/L received DNA screening for Duchenne, using the same dried blood spot. Results found that, of 37,649 males, only 308 had CK’s elevated above 750 U/L. Of these 308, 10 had CK’s above 2000 U/L. 6 of those 10 were found to have Duchenne gene mutations (single or multi-exon deletions, 5 out-of-frame and 1 in-frame). All 6 infants who were positive for Duchenne were found to have CKs above 2000 U/L. Infants with high CKs who were negative for Duchenne, were tested for the most common limb-girdle muscular dystrophies. Three were found to be positive.

 

This 2-step process was found to be compatible with maternity and newborn medical care in the US:

  • It was inexpensive (the cost of testing for CK levels on the dried blood was $1.00; the cost of DNA testing was $150).
  • The study determined a CK level above which DNA testing should be performed (750 U/L, which could possibly be raised to 1000 U/L), eliminating unnecessary DNA testing.
  • All testing was performed within the first 24-48 hours after birth (the length of time most mothers and newborns remain in the hospital) using a blood sample that is already being obtained.

 

While there were limitations with this, as with all studies, Mendell’s research may well provide a pathway for implementing newborn screening for Duchenne. As our research community continues to develop new therapies for Duchenne, having earlier diagnoses may ensure earlier implementation of these new therapies, improving the outcome for our boys. Jerry Mendell’s lab is to be commended for this amazing work.   

 

Read the details of Dr. Mendell’s study.

Kathi Kinnett RN/CNP is a friend of this community and someone you probably know from CCHMC, our Annual Connect Conference, and as one of the authors of the Care Considerations. We are so fortunate to have Kathi working with us on a variety of projects (as she has over the years), including this latest with newborn screening.

 


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Comment by Brian Denger on February 2, 2012 at 8:14pm

Thank you for posting this valuable information Kathi.

Certainly retesting for "false positives" will be a necessary consideration as well as providing families with appropriate DMD information should such a program be initiated. 

The current resistance to new born or infant screening is based in part by an opinion that there is no therapy for DMD.  Some families agree, yet in my speaking to many families, the consensus appears to favor screening.  Families understand there are things that can be done beyond the obvious such as family planning choices and choosing an appropriate residence for a child who may need specific accessibility requirements.  Early intervention for physical therapy (Avoiding inappropriate therapy that may harm muscle.), consideration of steroid and other medications is growing as well as educating families about participation in possible studies needing a younger cohort are all aspects that support newborn and/or infant screening.  It is also my understanding that efficacy will increase for therapies under development when started in younger patients.  Sure, some of this is still a few years out, but in order to be ready when additional options become available, patients and families will need to be prepared as well. 

Brian Denger

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