Screening newborn blood spots for 22q11.2 deletion syndrome using multiplex droplet digital PCR.
BACKGROUND
The diagnosis of 22q11 deletion syndrome (22q11DS) is often delayed or missed due to the wide spectrum of clinical involvement ranging from mild to severe, often life-threatening conditions. A delayed diagnosis can lead to life-long health issues that could be ameliorated with early intervention and treatment. Owing to the high impact of 22q11DS on public health, propositions have been made to include 22q11DS in newborn screening panels; however, the method of choice for detecting 22q11DS, fluorescent in situ hybridization, requires specialized equipment and is cumbersome for most laboratories to implement as part of their routine screening. We sought to develop a new genetic screen for 22q11DS that is rapid, cost-effective, and easily used by laboratories currently performing newborn screening.


METHODS
We evaluated the accuracy of multiplex droplet digital PCR (ddPCR) in the detection of copy number of 22q11DS by screening samples from 26 patients with 22q11DS blindly intermixed with 1096 blood spot cards from the general population (total n = 1122).


RESULTS
Multiplex ddPCR correctly identified all 22q11DS samples and distinguished between 1.5- and 3-Mb deletions, suggesting the approach is sensitive and specific for the detection of 22q11DS.


CONCLUSIONS
These data demonstrate the utility of multiplex ddPCR for large-scale population-based studies that screen for 22q11DS. The use of samples from blood spot cards suggests that this approach has promise for newborn screening of 22q11DS, and potentially for other microdeletion syndromes, for which early detection can positively impact clinical outcome for those affected.
Department of Biochemistry and Molecular Medicine, UC Davis Medical Center, Sacramento, CA;
Dalyir
D
Pretto
Digital Biology Center, Bio-Rad Laboratories, Pleasanton, CA;
Dianna
D
Maar
Department of Biochemistry and Molecular Medicine, UC Davis Medical Center, Sacramento, CA;
Carolyn M
CM
Yrigollen
Digital Biology Center, Bio-Rad Laboratories, Pleasanton, CA;
Jack
J
Regan
Department of Biochemistry and Molecular Medicine, UC Davis Medical Center, Sacramento, CA; MIND Institute, UC Davis Medical Center, Sacramento, CA. ftassone@ucdavis.edu.
Flora
F
Tassone
D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D004247:DNA / Q000097:blood / Q000235:genetics; D056915:DNA Copy Number Variations; D004062:DiGeorge Syndrome / Q000097:blood / Q000235:genetics; D059788:Dried Blood Spot Testing / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D017353:Gene Deletion; D059014:High-Throughput Nucleotide Sequencing / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D016133:Polymerase Chain Reaction / Q000295:instrumentation / Q000379:methods*
D004247:DNA