More info

Theory of the FISH method
Clinical applications (CATCH 22 syndrome)

The CATCH 22 syndrome is probably the most frequently encountered microdeletion syndrome with an incidence of 1: 4'000 to 5'000. It exhibits a large spectrum and a large variability in its features.

CATCH 22 stands for:

• C = cardiac (frequently Fallot tetralogy)
• A = abnomal faces
• T = thymic hypoplasia
• C = cleft palate
• H = hypocalcemia
• 22: 22q11 deletion

With a specific probe (red) the locus q11.2 of both chromosomes 22 are made visible. A second probe, which serves as a control probe, is used for marking the q11.13 region. On this karyogram, region q11.2 is missing on chromosome 22, indicating to a deletion.

When it is suspected clinically, the diagnosis is made with the FISH probe that specifically colors the 22q11.2 locus. If this region is absent (deletion) it cannot be tagged.