Immunodeficiency in 22q11.2 duplication syndrome

Abstract

Chromosome 22q11.2 contains specific low copy repeats (LCRs) that are prone to nonallelic homologous recombination, resulting in unequal crossovers during meiosis and thus genomic rearrangements.1 Changing the gene dosage in this region leads to many genomic disorders including 22q.11.2 deletion syndrome—the most common chromosome deletion syndrome at a prevalence of 1:3000 to 1:6000 live births—and the less well-characterized 22q11.2 duplication syndrome.2 First described in 1999, 22q11.2 duplication syndrome is estimated to occur at half the frequency of 22q11.2 deletion syndrome and presents with a broad phenotype and variable expressivity.