title: Evidence-based path to newborn screening for Duchenne muscular dystrophy.
abstract: OBJECTIVE
  Creatine kinase (CK) levels are increased on dried blood spots in newborns related to the birthing process. As a marker for newborn screening, CK in Duchenne muscular dystrophy (DMD) results in false-positive testing. In this report, we introduce a 2-tier system using the dried blood spot to first assess CK with follow-up DMD gene testing.
  
  
  METHODS
  A fluorometric assay based upon the enzymatic transphosphorylation of adenosine diphosphate to adenosine triphosphate was used to measure CK activity. Preliminary studies established a population-based range of CK in newborns using 30,547 deidentified anonymous dried blood spot samples. Mutation analysis used genomic DNA extracted from the dried blood spot followed by whole genome amplification with assessment of single-/multiexon deletions/duplications in the DMD gene using multiplex ligation-dependent probe amplification.
  
  
  RESULTS
  DMD gene mutations (all exonic deletions) were found in 6 of 37,649 newborn male subjects, all of whom had CK levels>2,000U/l. In 3 newborns with CK>2,000U/l in whom DMD gene abnormalities were not found, we identified limb-girdle muscular dystrophy gene mutations affecting DYSF, SGCB, and FKRP.
  
  
  CONCLUSIONS
  A 2-tier system of analysis for newborn screening for DMD has been established. This path for newborn screening fits our health care system, minimizes false-positive testing, and uses predetermined levels of CK on dried blood spots to predict DMD gene mutations.
authors.affiliation: Department of Pediatrics, Ohio State University and Nationwide Children's Hospital, Columbus, OH 43205, USA. Jerry.Mendell@nationwidechildrens.org
authors.forename: Jerry R
authors.initials: JR
authors.lastname: Mendell
authors.forename: Chris
authors.initials: C
authors.lastname: Shilling
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Leslie
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Flanigan
authors.forename: Roula
authors.initials: R
authors.lastname: al-Dahhak
authors.forename: Julie
authors.initials: J
authors.lastname: Gastier-Foster
authors.forename: Kelley
authors.initials: K
authors.lastname: Kneile
authors.forename: Diane M
authors.initials: DM
authors.lastname: Dunn
authors.forename: Brett
authors.initials: B
authors.lastname: Duval
authors.forename: Alexander
authors.initials: A
authors.lastname: Aoyagi
authors.forename: Cindy
authors.initials: C
authors.lastname: Hamil
authors.forename: Maha
authors.initials: M
authors.lastname: Mahmoud
authors.forename: Kandice
authors.initials: K
authors.lastname: Roush
authors.forename: Lauren
authors.initials: L
authors.lastname: Bird
authors.forename: Chelsea
authors.initials: C
authors.lastname: Rankin
authors.forename: Heather
authors.initials: H
authors.lastname: Lilly
authors.forename: Natalie
authors.initials: N
authors.lastname: Street
authors.forename: Ram
authors.initials: R
authors.lastname: Chandrasekar
authors.forename: Robert B
authors.initials: RB
authors.lastname: Weiss
mesh_terms: D019317:Evidence-Based Medicine / Q000379:methods*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis* / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D015997:Neonatal Screening / Q000379:methods*; D010865:Pilot Projects