The Dalglish Family 22q Clinic

Genetic testing is recommended for all individuals with the following:

• Intellectual, developmental, or learning disabilities, and/or history of
• Any developmental delay, including a delay in gross motor, fine motor, learning, and/or speech & language, and/or
• Congenital anomalies involving the heart (e.g., tetralogy of Fallot), palate (e.g., velopharyngeal insufficiency) and/or other systems.

Standard clinical testing using genome-wide microarray will detect 22q11.2 deletions and also other clinically relevant structural changes that may cause these major developmental conditions.

Source:
Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies.
Miller DT, Adam MP, Aradhya S, Biesecker LG, Brothman AR, Carter NP, Church DM, Crolla JA, Eichler EE, Epstein CJ, Faucett WA, Feuk L, Friedman JM, Hamosh A, Jackson L, Kaminsky EB, Kok K, Krantz ID, Kuhn RM, Lee C, Ostell JM, Rosenberg C, Scherer SW, Spinner NB, Stavropoulos DJ, Tepperberg JH, Thorland EC, Vermeesch JR, Waggoner DJ, Watson MS, Martin CL, Ledbetter DH.
Am J Hum Genet. 2010 May 14;86(5):749-64.
doi: 10.1016/j.ajhg.2010.04.006.

Clinical genetic testing is recommended for adults born with tetralogy of Fallot or other major congenital heart diseases (e.g. interrupted aortic arch, truncus arteriosus, ventricular septal defect):

As mentioned in the section above, genetic testing is recommended for those with intellectual disabilities / learning disabilities / developmental delays and any other congenital anomaly (birth defect). It is also recommended for those with:

• Psychiatric illnesses especially autism spectrum disorder, schizophrenia, attention deficit hyperactive disorder (ADHD), anxiety, or mood disorder
• Neurological conditions, such as epilepsy or cerebral palsy
• Scoliosis
• Multiple other medical conditions or multi-system complexity

Source:
Clinically Relevant Genetic Considerations for Patients With Tetralogy of Fallot
Bassett AS, Reuter MS, Malecki S, Silversides C, Oechslin E.
CJC Pediatr Congenit Heart Dis. 2023 Oct 10;2(6Part A):426-439.
doi: 10.1016/j.cjcpc.2023.10.002.

Genetic diagnostic testing is recommended to be considered for all adults who have schizophrenia. Clinical testing should be provided for all those with a history of developmental delay, intellectual disability or other congenital abnormalities as above. 1 in every 15 to 20 individuals with schizophrenia have copy number variants (CNVs) that may be clinically relevant. About 1% of individuals with schizophrenia have 22q11.2 deletions, and 1 in 4 individuals with 22q11.2 deletions develop schizophrenia some time in their life.

Source:
Chromosomal microarray analysis—a routine clinical genetic test for patients with schizophrenia
Baker K, Costain G, Fung WL, Bassett AS
Lancet Psychiatry. 1(5):329-31, 2014.
doi: 10.1016/S2215-0366(14)70308-6

Currently, in Ontario (and elsewhere in Canada, the UK, or the US), 22q11.2 deletion syndrome is not one of the conditions routinely screened in newborn babies .

There have been initiatives to add 22q11.2 deletions to the conditions recommended for regular newborn screening including in the UK and by the US Department of Health and Human Services’ Advisory Committee on Heritable Disorders in Newborns and Children.

Genetic screening is different from diagnostic genetic testing.

In Ontario, the 22q11.2 microdeletion is not part of the routine prenatal screening that is covered by OHIP. Some laboratories in Canada offer optional prenatal screening for 22q11.2 deletion using the pregnant mother’s blood sample as early as 9 weeks into the pregnancy for a cost.

There is an online petition that urges the American College of Obstetricians and Gynecologists to recommend 22q11.2 microdeletion screening for all pregnancies.

Diagnostic testing is recommended if the screening or fetal ultrasound shows an increased risk of having a genetic abnormality. Please see Prenatal Screening and Diagnostic Considerations for 22q11.2 Microdeletions for more information.