22q11.2 duplication syndrome

22q11.2 duplication syndrome
Synonyms	22q11.2 microduplication syndrome, DiGeorge syndrome duplication, velocardiofacial syndrome duplication
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Specialty	Medical genetics
Symptoms	Developmental delay, intellectual disability, learning disabilities, speech and language delays, congenital heart defects, cleft palate, immune system problems
Complications	N/A
Onset	Infancy or early childhood
Duration	Lifelong
Types	N/A
Causes	Genetic mutation (duplication of a small piece of chromosome 22)
Risks	Family history of the condition
Diagnosis	Genetic testing, chromosomal microarray analysis
Differential diagnosis	22q11.2 deletion syndrome, Down syndrome, autism spectrum disorder
Prevention	Genetic counseling
Treatment	Supportive care, speech therapy, occupational therapy, special education, surgery for heart defects or cleft palate
Medication	N/A
Prognosis	Varies; many individuals lead normal lives with appropriate support
Frequency	Estimated 1 in 4,000 live births
Deaths	N/A

Alternate names

22q11.2 duplication; 22q11.2 microduplication syndrome; Chromosome 22q11.2 duplication syndrome

Definition

22q11.2 duplication syndrome is a condition caused by an extra copy of a small piece of chromosome 22 which contains about 30 to 40 genes.

Cause

• People with 22q11.2 duplication have an extra copy of some genetic material at position q11.2 on chromosome 22.
• In most cases, this extra genetic material consists of a sequence of about 3 million DNA building blocks (base pairs), also written as 3 megabases (Mb).
• The 3 Mb duplicated region contains 30 to 40 genes.
• For many of these genes, little is known.
• A small percentage of affected individuals have a shorter duplication in the same region.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

• It is inherited in an autosomal dominant manner.
• While many affected people inherit the condition from a parent, others are affected due to having a new mutation that occurs for the first time.
• In either case, the condition can be passed on to children.

Signs and symptoms

• The features of this condition vary widely, even among members of the same family (intrafamilial variability).
• Affected individuals may have intellectual or learning disability, developmental delay, slow growth leading to short stature, and weak muscle tone (hypotonia).
• Many people with the condition have no apparent physical or intellectual disabilities.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

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)
• Depressed nasal ridge(Flat nose)
• Downslanted palpebral fissures(Downward slanting of the opening between the eyelids)
• Epicanthus(Eye folds)
• Global developmental delay
• High forehead
• [[Hypertelorism](Wide-set eyes)
• Intellectual disability(Mental deficiency)
• Midface retrusion(Decreased size of midface)
• Muscular hypotonia(Low or weak muscle tone)
• Narrow face(Decreased breadth of face)
• Nasal speech(Nasal voice)
• Neurological speech impairment(Speech disorder)

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)
• Attention deficit hyperactivity disorder(Attention deficit)
• Autism
• Displacement of the urethral meatus
• Growth delay(Delayed growth)
• Hearing impairment(Deafness)
• Hydronephrosis
• Hypoplastic left heart(Underdeveloped left heart)
• Interrupted aortic arch
• Microcephaly(Abnormally small skull)
• Micrognathia(Little lower jaw)
• Obsessive-compulsive behavior(Obsessive compulsive behavior)
• Ptosis(Drooping upper eyelid)
• Scoliosis
• Seizure
• Smooth philtrum
• Stereotypy(Repetitive movements)
• 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)

Diagnosis

The duplication is not detectable by karyotype and most cases are identified by a technique known as chromosomal microarray. <ref>Firth HV. 22q11.2 Duplication – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY. 2009 Feb 17 [Updated 2013 Nov 21]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK3823/</ref>[1].

Treatment

Treatment depends on the symptoms in each person and includes an individualized educational program.<ref>Firth HV. 22q11.2 Duplication – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY. 2009 Feb 17 [Updated 2013 Nov 21]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK3823/</ref>[2].

References

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NIH genetic and rare disease info

• NIH info on 22q11.2 duplication syndrome

22q11.2 duplication syndrome is a rare disease.