What Is 22q11 deletion syndrome

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Last updated: April 15, 2026

Quick Answer: 22q11.2 deletion syndrome is a genetic disorder caused by a microdeletion on chromosome 22 at the q11.2 region, affecting approximately 1 in 4,000 live births. It leads to a wide range of physical, developmental, and psychiatric issues, with symptoms varying widely among individuals.

Key Facts

Affects about 1 in 4,000 people, making it one of the most common microdeletion syndromes
Caused by a deletion of 30–40 genes on chromosome 22q11.2, typically occurring spontaneously
Over 180 clinical features are associated with the syndrome, including heart defects and cleft palate
80% of cases occur de novo, meaning neither parent carries the deletion
Diagnosed via FISH or chromosomal microarray testing, with diagnosis often delayed by years

Overview

22q11.2 deletion syndrome, also known as DiGeorge syndrome or velocardiofacial syndrome, is a genetic condition resulting from a small missing segment of chromosome 22. This deletion disrupts normal development and can affect multiple systems in the body, including the heart, immune system, and facial features.

Though symptoms vary widely, early diagnosis is critical for managing complications. The syndrome is underdiagnosed due to its variable expression, with many individuals not identified until later in childhood or adulthood.

Chromosome 22: The deletion occurs at the q11.2 region of chromosome 22, typically involving a loss of about 3 million base pairs.
Prevalence: Affects approximately 1 in 4,000 live births, though some estimates suggest it may be as common as 1 in 2,000.
Genes involved: The deleted region includes 30 to 40 genes, including TBX1, which plays a key role in embryonic development.
Onset: The condition is present from conception but may not be diagnosed until 2 to 3 years of age on average due to symptom variability.
Inheritance: About 80% of cases are de novo, while the remaining 20% are inherited in an autosomal dominant pattern.

How It Works

The syndrome arises from improper development during early embryogenesis, primarily due to the absence of key genes in the 22q11.2 region. These genes regulate tissue and organ formation, particularly in the pharyngeal arches, which give rise to facial, cardiac, and immune structures.

Microdeletion: A 30–40 gene loss on chromosome 22 disrupts normal signaling pathways, especially those involving TBX1 and COMT.
Cardiac defects:75% of patients have congenital heart anomalies, such as tetralogy of Fallot or truncus arteriosus.
Immune deficiency: Thymic hypoplasia leads to T-cell deficiency in about 77% of cases, increasing infection risk.
Palate abnormalities:70% of individuals experience velopharyngeal insufficiency or cleft palate, affecting speech and feeding.
Neurodevelopmental issues: Up to 40% develop ADHD, and 25% are diagnosed with autism spectrum disorder.
Psychiatric risk:25–30% of adults with 22q11.2 deletion develop schizophrenia, one of the highest known genetic risk factors.

Comparison at a Glance

Below is a comparison of 22q11.2 deletion syndrome with other common genetic disorders based on prevalence, genetic cause, and key features.

Condition	Prevalence	Genetic Cause	Key Features
22q11.2 deletion	1 in 4,000	Microdeletion chr22q11.2	Heart defects, immune deficiency, cleft palate, psychiatric disorders
Down syndrome	1 in 700	Trisomy 21	Intellectual disability, distinct facial features, heart defects
Williams syndrome	1 in 10,000	7q11.23 deletion	Hypercalcemia, cardiovascular disease, hypersociability
Prader-Willi	1 in 15,000	15q11–q13 deletion (paternal)	Obesity, hypotonia, behavioral issues
Turner syndrome	1 in 2,500 females	Monosomy X	Short stature, infertility, heart defects

This comparison highlights how 22q11.2 deletion syndrome is relatively common but often overlooked. Unlike Down syndrome, which is typically diagnosed at birth, 22q11.2 cases may go undetected for years due to milder or variable symptoms. Its multisystem involvement requires coordinated care across specialties, including cardiology, immunology, and psychiatry.

Why It Matters

Understanding 22q11.2 deletion syndrome is crucial for early intervention and long-term management. Because it affects so many body systems, timely diagnosis can significantly improve outcomes through targeted treatments and surveillance.

Early screening: Newborns with congenital heart defects should be tested for 22q11.2 deletion, as 1 in 6 with certain defects have the syndrome.
Psychiatric monitoring: Regular mental health evaluations are recommended starting in adolescence due to high schizophrenia risk.
Immunology care: Patients may require IVIG therapy or thymus transplantation in severe immune deficiency cases.
Educational support:70% have learning disabilities, necessitating individualized education plans (IEPs).
Genetic counseling: Families with one affected child have up to a 50% recurrence risk if a parent carries the deletion.
Research impact: Studying 22q11.2 provides insights into the genetics of schizophrenia and congenital anomalies.

Advances in genetic testing have improved diagnosis rates, but awareness among healthcare providers remains critical. With proper care, individuals with 22q11.2 deletion syndrome can lead productive lives, emphasizing the need for multidisciplinary, lifelong support.