22q1121

22q11.21 is a cytogenetic designation for a subregion on the long arm of chromosome 22, at band 11.21. It is used in human genetics to describe a locus that can be affected by copy number variations, including deletions or duplications. The region sits within the larger 22q11.2 area, which contains clusters of low-copy repeats that can predispose to non-allelic homologous recombination and recurrent rearrangements.

Clinical significance of variations at 22q11.21 is not as well defined as that of the more well-known 22q11.2 deletion syndrome. Copy number changes in this locus have been reported in individuals with a range of phenotypes, including congenital anomalies, neurodevelopmental disorders, and cardiac or endocrine features, as well as in some individuals without apparent health problems. Because the exact phenotypic outcome depends on the size of the alteration and the specific genes affected, predictions about clinical consequences remain limited.

Diagnosis typically relies on chromosomal microarray analysis (array CGH or SNP-based platforms) to detect deletions or duplications in the region. If a CNV is identified, genetic counseling and, when appropriate, parental testing can help determine inheritance and assess recurrence risk. Management is tailored to the individual’s clinical findings and often involves multidisciplinary care.

See also: 22q11.2 deletion syndrome; DiGeorge syndrome; velocardiofacial syndrome; copy number variation; low-copy repeats.