Refining the 22q11.2 deletion breakpoints in DiGeorge syndrome by aCGH

Area of Science:

• Genetics
• Genomics
• Human Molecular Genetics

Background:

• 22q11.2 deletion syndrome, also known as DiGeorge syndrome, presents with variable phenotypes.
• Recurrent deletions are attributed to low copy number repeats (LCRs) flanking the region.
• Breakpoint precise locations and their impact on phenotype remain incompletely understood.

Purpose of the Study:

• To precisely map the chromosomal breakpoints in individuals with 22q11.2 deletions.
• To investigate copy number variations (CNVs) across the genome in these individuals.
• To correlate breakpoint locations and CNVs with the variable clinical manifestations of 22q11.2 deletion syndrome.

Main Methods:

• Utilized high-resolution oligonucleotide-based 244K microarray comparative genomic hybridization (aCGH).
• Analyzed a cohort of 20 subjects with confirmed 22q11.2 deletions.
• Examined genome-wide copy number variation (CNV) in all subjects.

Main Results:

• Precisely delineated breakpoint regions for 22q11.2 deletions, occurring on either side of LCRs.
• Proximal breakpoints ranged from 17.036 to 17.398 Mb, distal breakpoints from 19.788 to 20.122 Mb.
• Identified 254 CNVs (94 duplications, 160 deletions) across the genome, varying in size.

Conclusions:

• Breakpoint locations influence the hemizygosity of genes within the deleted region.
• Genome-wide CNVs contribute to the phenotypic variability observed in 22q11.2 deletion syndrome.
• Precise breakpoint mapping and CNV analysis are crucial for understanding the complex genetics of this syndrome.