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Kobrynski L.J.,Emory University | Yazdanpanah G.K.,Newborn Screening Translational Research Initiative | Koontz D.,Centers for Disease Control and Prevention | Lee F.K.,Centers for Disease Control and Prevention | Vogt R.F.,Centers for Disease Control and Prevention
Clinical Chemistry | Year: 2016

BACKGROUND: A hemizygous deletion of 1.5-3 Mb in 22q11.2 causes a distinct clinical syndrome with variable congenital defects. Current diagnostic methods use fluorescent in situ hybridization (FISH) or comparative genomic hybridization by microarray to detect the deletion. Neither method is suitable for newborn screening (NBS), since they cannot be performed on dried blood spots (DBS). We developed a MALDITOF-MS assay that uses DBS to measure the hemizygous deletion of UFD1L, located within the 22q11.2 region. METHODS: We used DBS from 54 affected patients, previously tested by FISH or microarray, and 100 cord blood samples to evaluate the performance of the MALDI-TOF-MS assay. With a single primer pair, a 97-base oligonucleotide within UFD1L was amplified, as was a sequence on chromosome 18 that differs by 2 nucleotides. A multiplexed, single-base extension reaction created allele-specific products for MALDITOF-MS detection. The products were spotted onto a silicon chip, and the height of the spectral peaks identified the relative amounts of target and reference gene. RESULTS: The median ratio of the spectral peak for each UFD1L target:reference base was 0.96 and 0.99 for controls, compared with 0.35 and 0.53 for 22q11 deletion syndrome patients. There was 100% concordance between FISH/microarray and MALDI-TOF-MS in all patients with 22q11.2 deletion syndrome. CONCLUSIONS: This method can be reliably performed with DBS and is suitable for high sample throughput. This assay may be considered for use in population-based NBS for 22q11.2 deletion. © 2015 American Association for Clinical Chemistry.


PubMed | Centers for Disease Control and Prevention, Newborn Screening Translational Research Initiative and Emory University
Type: Journal Article | Journal: Clinical chemistry | Year: 2015

A hemizygous deletion of 1.5-3 Mb in 22q11.2 causes a distinct clinical syndrome with variable congenital defects. Current diagnostic methods use fluorescent in situ hybridization (FISH) or comparative genomic hybridization by microarray to detect the deletion. Neither method is suitable for newborn screening (NBS), since they cannot be performed on dried blood spots (DBS). We developed a MALDI-TOF-MS assay that uses DBS to measure the hemizygous deletion of UFD1L, located within the 22q11.2 region.We used DBS from 54 affected patients, previously tested by FISH or microarray, and 100 cord blood samples to evaluate the performance of the MALDI-TOF-MS assay. With a single primer pair, a 97-base oligonucleotide within UFD1L was amplified, as was a sequence on chromosome 18 that differs by 2 nucleotides. A multiplexed, single-base extension reaction created allele-specific products for MALDI-TOF-MS detection. The products were spotted onto a silicon chip, and the height of the spectral peaks identified the relative amounts of target and reference gene.The median ratio of the spectral peak for each UFD1L target:reference base was 0.96 and 0.99 for controls, compared with 0.35 and 0.53 for 22q11 deletion syndrome patients. There was 100% concordance between FISH/microarray and MALDI-TOF-MS in all patients with 22q11.2 deletion syndrome.This method can be reliably performed with DBS and is suitable for high sample throughput. This assay may be considered for use in population-based NBS for 22q11.2 deletion.

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