How is 22q11.2 deletion syndrome diagnosed?
Prior to birth:
1. Family health history – if a parent has 22q, there is a 50% chance the child will
2. NIPT (non-invasive prenatal testing) blood draw – does not harm the fetus; determines the risk that the fetus will be born with certain genetic abnormalities; analyzes the DNA cells in a pregnant woman’s bloodstream which at the time of being pregnant is a mix of her cells and the placenta’s cells; this test is only a “screening” so accuracy varies and there can be false positives and/or false negatives; NIPT could also detect a genetic condition in the mother; a positive NIPT result indicates that further testing should be done
3. Amniocentesis – invasive testing with possible risk(s); using a needle, a sample of amniotic fluid is removed from the uterus for DNA testing; this test might be suggested if a previous screening indicated positive results, if an earlier pregnancy was affected by a genetic condition, if there is a family history or a parent is a carrier, or if there are unusual ultrasound findings
4. CVS (chorionic villus sampling) – invasive testing with possible risk(s); either by catheter into the cervix or needle into the abdomen, a sample is taken from the placenta for DNA testing; this test might be suggested if a previous screening indicated positive results, if an earlier pregnancy was affected by a genetic condition, if there is a family history or a parent is a carrier, or if there are unusual ultrasound findings
5. Fetal echocardiogram – prenatal ultrasound of the baby’s heart; no risk to baby or mother
After birth:
1. Physical exam – could show signs that something needs further assessed
2. Newborn screening – a small blood sample “heel stick” is collected from every newborn within 48 hours of birth and sent to a lab for testing (Izzy’s showed abnormal T cell count.)
3. X-rays, CT scans, MRI
4. Echocardiogram – ultrasound of the baby’s heart
5. FISH (fluorescent in situ hybridization) – a lab technique that uses the baby’s blood sample and fluorescent dye to detect and locate a specific DNA sequence on a chromosome; can look specifically for a deleted gene
6. Chromosomal microarray blood test (chromosome study) – blood sample is taken from the child and their DNA is compared to a control sample to look for deletions or duplications (This is how Izzy was diagnosed.)