Assessment of liquid microbead arrays for the screening of newborns for spinal muscular atrophy.
BACKGROUND
Spinal muscular atrophy is a common neurodegenerative disorder that has recently been considered for inclusion in the next generation of newborn screening regimens. We sought to validate liquid microbead arrays for the identification of affected individuals by direct DNA analysis.


METHODS
Assays were created to detect the homozygous deletions in exon 7 of the SMN1 gene found in approximately 95% of affected individuals by use of 2 different microbead chemistries on the Luminex 200: MultiCode-PLx and Tag-It. A series of 367 blood spots including 164 from affected individuals, 46 from known carriers, and 157 from unaffected individuals were then analyzed with each assay.


RESULTS
The MultiCode-PLx assay required 4.2 h to perform and provided correct identification of all 164 samples from affected individuals. Correct exclusion was also made for all 46 carrier and 157 unaffected individual samples. The Tag-It assay required 6.8 h, detected all samples from affected individuals, and excluded all but 1 (99.5%) of the samples from carriers and unaffected individuals. Neither method was sensitive to increasing copy numbers of the SMN2 gene.


CONCLUSIONS
Both methods showed high sensitivity and specificity for the detection of patients with spinal muscular atrophy. For both methods, ample DNA was extracted from all blood spots for analysis, and SMN2 copy numbers did not interfere. Liquid bead arrays represent a robust method for DNA analysis in newborn screening laboratories.
Pyatt
Robert E
RE
Department of Pathology, Ohio State University, Columbus, OH 43210, USA.
Mihal
David C
DC
Prior
Thomas W
TW
D016000:Cluster Analysis; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D004247:DNA / Q000097:blood; D017353:Gene Deletion; D018628:Gene Dosage; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007231:Infant, Newborn; D008863:Microspheres; D015997:Neonatal Screening / Q000379:methods*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D055532:SMN Complex Proteins; D012680:Sensitivity and Specificity; D014897:Spinal Muscular Atrophies of Childhood / Q000175:diagnosis* / Q000235:genetics; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; C526477:SMN2 protein, human; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D004247:DNA