Genomic copy number aberrations at the chromosomal region 22q11 are frequently observed and are the cause of multiple disorders, including DiGeorge syndrome, Velocardiofacial syndrome (VSFS) and Cat eye syndrome. Greater than 90% of all DiGeorge cases are due to a microdeletion at the 22q11 region. DiGeorge syndrome is characterized by neonatal hypocalcaemia, susceptibility to infections due to T-lymphocyte abnormalities, distinctive facial features and a variety of heart dysplasias. Short stature and mild to moderate learning disabilities are also quite frequent, alongside various psychiatric disorders including schizophrenia and severe depression. Prevalence of this syndrome is 1/4000 births.
We perform an MLPA technique, employing multiple probes recognizing specific DNA sequences in the region of interest, enabling us to detect deletions of specific sequences within the 22q11-13 region, known to be responsible for >95% of all DiGeorge and Velocardiofacial syndrome cases. Also, the same technique allows us to detect an increase in the copy number of the 22q11 region (usually presenting in the form of a supernumerary mini-chromosome), considered to be responsible for the development of Cat eye syndrome. Finally, deletions/duplications of the chromosomal regions 10p13/14(DGS24), 4q34.2 and 8p23 are also interrogated, as they may lead to clinical symptoms similar to the ones associated with classic DiGeorge syndrome.