XL DiGeorge TBX1 consists of an orange-labeled probe hybridizing to the TBX1 gene region at 22q11.2 and a green-labeled probe hybridizing to the SHANK3 gene region at 22q13.3.

Probe maps are created in accordance with the intended purpose of the product. Solid colored bars do not necessarily indicate that the probe fully covers the indicated genomic region. Therefore, caution is advised when interpreting results generated through off-label use. Probe map details based on UCSC Genome Browser GRCh37/hg19. Map components not to scale. Further information is available on request.

22q11.2 deletion syndrome (22q11.2DS) includes the DiGeorge- and Velo-cardio-facial syndrome and is the most common microdeletion syndrome. Up to 95% of the deletions identified occur de novo and are not inherited. 22q11.2DS related de novo deletions are mediated by non-allelic inter- and intrachromosomal homologous recombination between low copy number repeats on chromosome 22. A deletion of 3 Mb overlapping about 90 genes, is detected in the vast majority of 22q11.2DS cases whereas a smaller fraction is identified with a nested deletion of about 1.5Mb overlapping with about 55 genes. One of the most thoroughly investigated genes in this region is the T-box transcription factor 1 (Tbx1). Tbx1 is phylogenetically conserved and has manifold functions during embryonic development. Studies using mouse as a model organism have shown that Tbx1 is a key determinant in 22q11.2DS.

Clinical Applications

• Microdeletion Syndrome (MicroDel)

XL DiGeorge TBX1 hybridized to lymphocytes. One normal metaphase is shown.

• Edelmann et al (1999) Am J Hum Genet 64:1076-1086
• Jerome and Papaioannou (2001) Nature Genet 27:286-291
• McDonald-McGinn et al (2015) Nat Rev Dis Primers 1:1-19