Result of FISH analysis using LSI probe (TUPLE 1) from<unk> /velocardiofacial syndrome critical region. TUPLE 1 (HIRA) probe was labeled in Spectrum Orange and Arylsulfatase A (ARSA) in Spectrum Green as control. Absence of the orange signal indicates deletion of the TUPLE 1 locus at 22q11.2. Brain computer tomography cuts of the person, demonstrating basal ganglia and periventricular calcification. Diagnosis of<unk>  can be difficult due to the number of potential symptoms and the variation in phenotypes between individuals. It is suspected in patients with one or more signs of the deletion. In these cases a diagnosis of 22q11.2DS is confirmed by observation of a deletion of part of the long arm (q) of chromosome 22, region 1, band 1, sub-band 2. Genetic analysis is normally performed using fluorescence in situ hybridization (FISH), which is able to detect microdeletions that standard karyotyping (e.g. G-banding) miss. Newer methods of analysis include Multiplex ligation-dependent probe amplification assay (MLPA) and quantitative polymerase chain reaction (qPCR), both of which can detect atypical deletions in 22q11.2 that are not detected by FISH. qPCR analysis is also quicker than FISH, which can have a turn around of 3 to 14 days. A 2008 study of a new high-definition MLPA probe developed to detect copy number variation at 37 points on chromosome 22q found it to be as reliable as FISH in detecting normal 22q11.2 deletions. It was also able to detect smaller atypical deletions that are easily missed using FISH. These factors, along with the lower expense and easier testing mean that this MLPA probe could replace FISH in clinical testing. Genetic testing using BACs-on-Beads has been successful in detecting deletions consistent with 22q11.2DS during prenatal testing. Array-comparative genomic hybridization (array-CGH) uses a large number of probes embossed in a chip to screen the entire genome for deletions or duplications. It can be used in post and pre-natal diagnosis of 22q11.2. Fewer than 5% of individuals with symptoms of<unk>  have normal routine cytogenetic studies and negative FISH testing. In these cases, atypical deletions are the cause. Some cases of 22q11.2 deletion syndrome have defects in other chromosomes, notably a deletion in chromosome region 10p14.
DiGeorge syndrome
Smith–Lemli–Opitz syndrome
Langer–Giedion syndrome
Alagille syndrome
ATR-16 syndrome
Goldenhar syndrome
ATR-X syndrome
VACTERL association