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If you have read the Our Story then you know that we lost our first child, Jackson, to a chromosome abnormality called Trisomy 18. Because we lost Jackson to Trisomy 18, and with James having so many issues when he was born, the doctors decided to run some genetic tests to see if any of James’ issues were genetic related. One of the things that they discovered was that James has something called 22q11.2 duplication. This means that he has an extra piece of chromosome 22.
I’ll admit that when I heard the words “chromosome 22” and “extra” in the same sentence, I was a little freaked out. After losing Jackson to Trisomy 18 and knowing that Down Syndrome is Trisomy 21, I knew that having an extra chromosome can cause many health and developmental issues. The geneticist stressed that 22q11.2 duplication is not an extra copy of a chromosome like in Trisomy 18 or 21, but just an extra “piece” so although there may be some health and developmental concerns, they won’t be as severe as with a complete extra chromosome.
Okay, so if we are not dealing with a complete Trisomy here, what are we looking at? What issues can we expect this extra “piece” of chromosome 22 to cause? Those are just a couple of the questions that I aim to answer here. I won’t go too deep into all the medical mumbo jumbo, but will instead just provide a general overview of what it is, and the possible issues it may cause. If you would like to learn more about 22q11.2 duplication, please visit the websites that I have referenced below.
What is 22q11.2 duplication?
The US National Library of Medicine Genetics Home Reference says that “22q11.2 duplication is a condition caused by an extra copy of a small piece of chromosome 22. The duplication occurs near the middle of the chromosome at a location designated q11.2.”
They continue by saying that “the features of this condition vary widely, even among members of the same family. Affected individuals may have developmental delay, intellectual disability, slow growth leading to short stature, and weak muscle tone (hypotonia). Many people with the duplication have no apparent physical or intellectual disabilities.”
When James was in the NICU, it was noted in one of our family meetings that he has muscle tone abnormalities: hypertonic in the legs and hypotonic in the trunk. We’re not sure if this is part of the 22q11.2 duplication or if this is because of his cerebral palsy. Maybe it’s a combination of the two?
The other symptoms mentioned above (developmental delay and intellectual disability) could also be part of the CP or it could be part of the 22q11.2 duplication. We just don’t know.
Symptoms of 22q11.2 duplication
A few symptoms were mentioned above in the US National Library of Medicine Genetics Home Reference’s description of 22q11.2 duplication.
The Genetic and Rare Diseases Information Center has a much more extensive list:
| Medical Terms | Other Names |
|---|---|
| 30%-79% of people have these symptoms | |
| Abnormality of the pharynx | |
| Cleft palate | Cleft roof of mouth |
| Delayed speech and language development | Deficiency of speech development Delayed language development Delayed speech Delayed speech acquisition Delayed speech development Impaired speech and language development Impaired speech development Language delay Language delayed Language development deficit Late-onset speech development Poor language development Speech and language delay Speech and language difficulties Speech delay |
| Depressed nasal ridge | Flat nose Recessed nasal ridge |
| Downslanted palpebral fissures | Downward slanting of the opening between the eyelids |
| Epicanthus | Eye folds Prominent eye folds |
| Global developmental delay | |
| High forehead | |
| Hypertelorism | Wide-set eyes Widely spaced eyes |
| Intellectual disability | Mental deficiency Mental retardation Mental retardation, nonspecific Mental-retardation |
| Midface retrusion | Decreased size of midface Midface deficiency Underdevelopment of midface |
| Muscular hypotonia | Low or weak muscle tone |
| Narrow face | Decreased breadth of face Decreased width of face |
| Nasal speech | Nasal voice |
| Neurological speech impairment | Speech disorder Speech impairment Speech impediment |
| Medical Terms | Other Names |
| 5%-29% of people have these symptoms | |
| Abnormality of immune system physiology | |
| Anterior creases of earlobe | Earlobe crease |
| Anxiety | Excessive, persistent worry and fear |
| Aplasia/Hypoplasia of the thymus | Absent/small thymus Absent/underdeveloped thymus |
| Attention deficit hyperactivity disorder | Attention deficit Attention deficit disorder Attention deficit-hyperactivity disorder Attention deficits Childhood attention deficit/hyperactivity disorder |
| Autism | |
| Displacement of the urethral meatus | |
| Growth delay | Delayed growth Growth deficiency Growth failure Growth retardation Poor growth Retarded growth |
| Hearing impairment | Deafness Hearing defect |
| Hydronephrosis | |
| Hypoplastic left heart | Underdeveloped left heart |
| Interrupted aortic arch | |
| Microcephaly | Abnormally small skull Decreased circumference of cranium Decreased size of skull Reduced head circumference Small head circumference |
| Micrognathia | Little lower jaw Small jaw Small lower jaw |
| Obsessive-compulsive behavior | Obsessive compulsive behavior |
| Ptosis | Drooping upper eyelid |
| Scoliosis | |
| Seizure | |
| Smooth philtrum | |
| Stereotypy | Repetitive movements Repetitive or self-injurious behavior |
| Tetralogy of Fallot | |
| Transposition of the great arteries | |
| Urethral stenosis | Narrowing of the urethra |
| Ventricular septal defect | Hole in heart wall separating two lower heart chambers |
| Wide nose | Broad nose Increased breadth of nose Increased nasal breadth Increased nasal width Increased width of nose |
| Medical Terms | Other Names |
| Percent of people who have these symptoms is not available through HPO | |
| Abnormality of cardiovascular system morphology | |
| Abnormality of the pinna | Abnormally shaped ears Auricular malformation Deformed ears Malformed ears |
| Autosomal dominant inheritance | |
| Generalized hypotonia | Decreased muscle tone Low muscle tone |
| High palate | Elevated palate Increased palatal height |
| Low-set ears | Low set ears Lowset ears |
| Specific learning disability | |
| Sporadic | No previous family history |
| Velopharyngeal insufficiency | Velopharyngeal incompetence |
As with most diseases, not all individuals will exhibit the same symptoms. Some individuals with 22q11.2 duplication may have a certain symptom in the above list, while another individual may not.
And remember, as noted by The US National Library of Medicine Genetics Home Reference, some individuals who have 22q11.2 duplication may not show any symptoms. Stacy, for example, also has 22q11.2 duplication, and other than a slight learning disability, she does not have any obvious symptoms.
Looking through the above list, we can say that James has the following symptoms of 22q11.2 duplication:
- Delayed speech and language development
- Global developmental delay
- Intellectual disability
- Muscular hypotonia
- Neurological speech impairment
- Abnormality of immune system physiology
- Hearing impairment
- Scoliosis
- Seizure
- Generalized hypotonia
- High palate
Conclusion
As you can see, 22q11.2 duplication can cause a range of issues; some severe, others not. 22q11.2 duplication affects everyone differently. James has several issues that may, or may not be caused by his 22q11.2 duplication, but Stacy only has a slight learning disability.
This was just a brief overview of 22q11.2 duplication. I did not intend for it to be an “everything you should know” type article. If you would like to learn more about 22q11.2 duplication, here are the websites I used for this article:
- Genetic and Rare Diseases Information Center
- US National Library of Medicine Genetics Home Reference