Heart defects are one of the most frequent and medically urgent features of DiGeorge syndrome, occurring in roughly three-quarters of affected individuals. The syndrome, caused by a small missing piece of chromosome 22, disrupts normal heart development before birth, producing a specific pattern of structural problems centered on the outflow vessels of the heart. The defects most commonly seen include tetralogy of Fallot, interrupted aortic arch, and truncus arteriosus, all of which typically require surgical correction in infancy. Treatment is effective but complicated by the syndrome’s effects on the immune system, calcium regulation, and development.
What Causes DiGeorge Syndrome and Why the Heart Is So Affected
DiGeorge syndrome results from a missing stretch of DNA on chromosome 22, known as a 22q11.2 deletion. This deletion spans roughly 1.5 to 3 million base pairs and removes several genes at once.1PubMed. TBX1 is responsible for cardiovascular defects in velo-cardio-facial/DiGeorge syndrome Among the lost genes, one called TBX1 stands out as the primary driver of the heart problems. Mouse studies have shown that reducing TBX1 by just half is enough to produce the same kinds of outflow tract defects seen in people with the syndrome, and that adding the human version of the gene back can partially rescue those defects.2PubMed Central. Understanding the role of Tbx1 as a candidate gene for 22q11.2 deletion syndrome The syndrome occurs in roughly 1 in 3,000 live births, making it one of the more common chromosomal deletion disorders even though many clinicians still think of it as rare.
The heart is so heavily affected because the deleted genes play a critical role in a group of embryonic cells called cardiac neural crest cells. These cells migrate from the developing spinal region into the heart and the arteries branching off from it. Their job is to help separate the single outflow vessel that every embryo starts with into the distinct aorta and pulmonary artery, and to sculpt the aortic arch arteries into their final adult pattern.3PubMed Central. Cardiac Neural Crest In DiGeorge syndrome the neural crest cells still reach the heart, but they fail to mature properly into the smooth-muscle cells that stabilize these vessels. The result is that the arch arteries form abnormally or incompletely, and the outflow tract does not divide the way it should.4PubMed. The role of neural crest during cardiac development in a mouse model of DiGeorge syndrome This same developmental pathway also builds the thymus and parathyroid glands, which explains why DiGeorge syndrome affects the immune system and calcium levels alongside the heart.
Tetralogy of Fallot
Tetralogy of Fallot is the single most common heart defect in DiGeorge syndrome and one of the defects most strongly linked to the 22q11.2 deletion in general. In studies of children with tetralogy of Fallot, roughly 15 to 18 percent carry the deletion.5PubMed. Frequency of 22q11 deletions in patients with conotruncal defects 6PubMed Central. 22q11.2 deletion status and disease burden in children and adolescents with tetralogy of Fallot Tetralogy of Fallot involves four linked abnormalities: a hole between the lower chambers of the heart, narrowing of the passage to the lungs, an aorta that straddles both ventricles instead of only the left, and thickening of the right ventricle wall. Together these cause oxygen-poor blood to bypass the lungs and enter the body, giving the baby a bluish color.
When tetralogy of Fallot occurs alongside DiGeorge syndrome, it tends to be on the more severe end. Patients with the deletion are more likely to have complete absence of the pulmonary valve rather than just narrowing, a variant known as tetralogy of Fallot with pulmonary atresia. In one study of 123 patients with tetralogy of Fallot, those who carried the 22q11.2 deletion were significantly more likely to have pulmonary atresia than those without the deletion.7International Journal of Cardiology. Frequency of 22q11.2 microdeletion in sporadic non-syndromic tetralogy of Fallot cases Children with DiGeorge syndrome and tetralogy of Fallot are also more likely to have additional abnormalities of the pulmonary arteries, the aortic arch, or the branching vessels, which can complicate surgical planning.
Interrupted Aortic Arch
Interrupted aortic arch, especially the type B variant where the gap is located between the left common carotid artery and the left subclavian artery, has the strongest association with DiGeorge syndrome of any heart defect. About half of all babies born with type B interrupted aortic arch carry the 22q11.2 deletion.8The American Journal of Cardiology. A Genetic Etiology for Interruption of the Aortic Arch Type B Some studies have reported rates over 60 percent.9Progress in Pediatric Cardiology. DiGeorge syndrome: Implications for aortic arch obstruction In this defect the aorta simply stops partway through its arch, leaving the lower body dependent on a temporary fetal vessel, the ductus arteriosus, for blood flow. When that vessel closes naturally after birth, the situation becomes life-threatening within hours. Surgical repair during the newborn period is essential.
Because the association is so strong, guidelines recommend genetic testing for the 22q11.2 deletion in every newborn found to have type B interrupted aortic arch. Identifying the deletion early helps coordinate the additional care these babies need for immune deficiency and low calcium, both of which can cause serious complications during and after surgery.
Truncus Arteriosus
Truncus arteriosus occurs when the single outflow vessel of the embryonic heart never divides into a separate aorta and pulmonary artery. The baby is born with one large vessel leaving the heart, supplying blood to the body, the lungs, and the coronary arteries all at once. Roughly a third of children with truncus arteriosus carry the 22q11.2 deletion.5PubMed. Frequency of 22q11 deletions in patients with conotruncal defects The defect was actually one of the earliest heart problems described in families with DiGeorge syndrome. A 1981 case report documented three out of four siblings with truncus arteriosus and other features consistent with the syndrome, hinting at the genetic basis long before the 22q11.2 deletion was identified.10Pediatrics. Familial Third and Fourth Pharyngeal Pouch Syndrome with Truncus Arteriosus: DiGeorge Syndrome
When truncus arteriosus occurs with DiGeorge syndrome, surgeons sometimes encounter additional complications such as major aortopulmonary collateral arteries, extra vessels that the body grows to supply blood to the lungs when the normal route is inadequate, or narrowing at the origin of the pulmonary arteries from the common trunk.11PubMed. Truncus arteriosus communis associated with chromosome 22q11 deletion These extras add layers of complexity to the repair. Because truncus arteriosus requires placement of a conduit between the right ventricle and the pulmonary arteries, children typically need additional surgeries as they outgrow the conduit.
Aortic Arch Anomalies and Vascular Rings
Beyond the three headline defects, DiGeorge syndrome produces a wide range of abnormalities in the aortic arch and its branches. These are often present alongside one of the major defects but can also appear in isolation. The list includes right-sided aortic arch, aberrant origin of a subclavian artery, cervical aorta (an unusually high arch that reaches into the neck), absent ductus arteriosus, and vascular rings that encircle and potentially compress the esophagus or airway.12PubMed. Aortic arch anomalies associated with chromosome 22q11 deletion (CATCH 22) These anomalies are significantly more common in patients with the 22q11.2 deletion than in patients who have the same intracardiac defect without the deletion, reinforcing how heavily the deletion affects the vessels that develop from the pharyngeal arch arteries.
Vascular rings can cause feeding difficulties and breathing problems that sometimes go unexplained for months before the anatomy is worked out. Ventricular septal defects, holes between the heart’s lower chambers, also appear frequently in DiGeorge syndrome but tend to be less surgically complex than the outflow tract defects.
How Diagnosis Happens Before and After Birth
Prenatal detection of the 22q11.2 deletion has improved over the past decade. Noninvasive prenatal screening using cell-free fetal DNA in the mother’s blood can be performed from about 10 weeks of pregnancy and picks up roughly 70 to 83 percent of 22q11.2 deletions, though the positive predictive value runs around 40 to 50 percent, meaning a positive screen needs to be confirmed by amniocentesis or chorionic villus sampling.13PubMed Central. Prenatal Screening and Diagnostic Considerations for 22q11.2 Microdeletions A Taiwanese study of nearly 8,000 pregnancies found a prevalence of about 1 in 1,100 pregnancies screened and confirmed a positive predictive value of around 54 percent.14PubMed. Taiwanese Clinical Experience with Noninvasive Prenatal Testing for DiGeorge Syndrome
Ultrasound can also raise suspicion when it reveals a heart defect, particularly one of the outflow tract defects. Among the prenatal signs, conotruncal heart anomalies are the most strongly associated with the deletion. Other ultrasound findings such as absent or small thymus, kidney anomalies, or cleft palate add to the clinical suspicion but are less specific on their own.
After birth, many cases are identified because a baby presents with a significant heart defect, especially interrupted aortic arch type B or truncus arteriosus, and genetic testing is ordered. Others come to attention through newborn screening programs that detect T-cell deficiency or through the evaluation of unexplained low calcium. Chromosomal microarray or targeted fluorescence in situ hybridization confirms the deletion definitively.
Surgical Repair and What Makes It Different
Most children with DiGeorge syndrome and a major heart defect undergo open-heart surgery in the first weeks or months of life. The surgical techniques are the same ones used for any child with the same structural defect. For interrupted aortic arch, surgeons reconnect the aortic segments directly. For tetralogy of Fallot, they close the ventricular septal defect and relieve the obstruction to the pulmonary artery. For truncus arteriosus, they separate the pulmonary arteries from the common trunk and place a conduit from the right ventricle to the pulmonary circulation. What differs is the postoperative course.
A retrospective study comparing DiGeorge syndrome patients to matched controls after cardiac surgery found that although survival rates were the same (100 percent in both groups), children with DiGeorge syndrome had significantly longer hospital stays, averaging about 77 days compared to roughly 34 days for controls. They spent more time on mechanical ventilation (about 43 days versus 9 days) and more time in intensive care (about 30 days versus 12 days). They also experienced more infections, including surgical site infections, urinary tract infections, and ventilator-associated pneumonia.15PubMed Central. The Outcomes of Cardiac Surgery in Children With DiGeorge Syndrome in a Single Center Experience: A Retrospective Cohort Study These differences stem from the syndrome’s effects on the immune system and other organ systems, not from anything inherently different about the cardiac repair itself.
Perioperative Risks Unique to DiGeorge Syndrome
Two complications deserve special attention because they are specific to DiGeorge syndrome and can be dangerous if surgical teams are not prepared for them.
The first is hypocalcemia. Because the parathyroid glands are often underdeveloped or absent in DiGeorge syndrome, calcium levels can drop dangerously during and after surgery. In one case series, two patients developed persistent low calcium during the operation requiring continuous calcium infusion, and eight more developed hypocalcemia after surgery.16Journal of Cardiothoracic and Vascular Anesthesia. Perioperative Management of Patients With DiGeorge Syndrome Undergoing Cardiac Surgery Low calcium can trigger seizures and dangerous heart rhythms, so careful monitoring and proactive supplementation are standard practice.
The second is the risk of transfusion-associated graft-versus-host disease. Because many DiGeorge syndrome patients have severely reduced T-cell counts, their immune systems cannot destroy donor white blood cells that come along with transfused blood products. Those donor cells can attack the patient’s own tissues, a reaction that is frequently fatal. A documented case involved an infant who died of graft-versus-host disease after receiving non-irradiated blood during surgery for tetralogy of Fallot.17Cardiology in the Young. Transfusion associated graft-versus-host disease in DiGeorge syndrome The prevention is straightforward: all blood products given to DiGeorge syndrome patients should be irradiated to eliminate donor white blood cells. Screening T-cell counts before surgery helps identify which patients are most at risk.
Neurodevelopmental Effects in Children With Critical Heart Defects
Children with DiGeorge syndrome who undergo heart surgery in the newborn period face a double challenge. They carry the neurodevelopmental risks that come with any complex neonatal cardiac surgery, plus the independent effects of the 22q11.2 deletion on brain development. A study comparing neonates with and without the deletion after surgery for critical heart defects found sharply different outcomes. Mental developmental scores averaged about 66 in the deletion group versus about 86 in those without it. Psychomotor scores showed an even wider gap, averaging roughly 55 versus 82. Mental delay occurred in about 62 percent of the deletion group compared to about 14 percent of those without the deletion, and psychomotor delay occurred in about 85 percent versus about 7 percent.18The Journal of Thoracic and Cardiovascular Surgery. Neurodevelopmental outcome of neonates with chromosome 22q11.2 deletion syndrome and critical congenital heart disease
The deletion itself accounted for a large share of the variation in these scores, meaning the genetic syndrome contributes to developmental delays beyond whatever effect the heart surgery alone has. This finding has practical implications: early developmental support, physical therapy, and speech therapy should begin as soon as possible after surgical recovery, rather than waiting to see how the child develops on their own.
Long-Term Survival in Adults
Advances in cardiac surgery mean that most children with DiGeorge syndrome now survive their initial heart repairs and reach adulthood. However, the severity of the original heart defect continues to affect survival over the long term. A study tracking adults with 22q11.2 deletion syndrome found that those with a major congenital heart defect had a roughly 82 percent probability of surviving to age 40 and about 63 percent probability of surviving to age 50. By comparison, those without a major heart defect had a 98 percent probability of reaching 40 and about 85 percent of reaching 50. The median age at death was about 37 years for the major heart defect group versus about 51 years for those without one.19Genetics in Medicine. All-cause mortality and survival in adults with 22q11.2 deletion syndrome
That said, heart defects are not the only cause of reduced life expectancy in this population. The deletion syndrome itself carries risks of psychiatric illness, autoimmune disease, and other conditions that accumulate over time. A separate study found that a history of congenital heart disease was not a significant predictor of overall functional outcomes in adults with the syndrome, suggesting that the heart problem alone does not define quality of life once it has been successfully repaired.20PubMed Central. Functional outcomes of adults with 22q11.2 deletion syndrome Psychiatric conditions, particularly mood and anxiety disorders, and chronic health management play larger roles in daily functioning.
Why Multidisciplinary Care Matters
DiGeorge syndrome is not just a heart condition, and treating it as one leads to gaps in care. A child might undergo a flawless cardiac repair but then face recurrent infections due to immune deficiency, seizures from low calcium, feeding difficulties from palatal or swallowing problems, or speech delays from a combination of all of the above.21PubMed. Updated clinical practice recommendations for managing adults with 22q11.2 deletion syndrome Even non-cardiac surgeries later in life, like an orchidopexy for an undescended testicle, present unique anesthetic challenges because of the syndrome’s effects on the airway, calcium regulation, and immune function.22PubMed Central. Anaesthesia concerns and perioperative management in a child with DiGeorge syndrome with corrected tetralogy of Fallot with pulmonary atresia posted for laparoscopic orchidopexy
The coordinated involvement of cardiology, immunology, endocrinology, genetics, developmental pediatrics, and eventually psychiatry reflects the reality that the 22q11.2 deletion affects nearly every organ system. Updated clinical practice recommendations emphasize that this integrated approach should continue into adulthood, not end when the cardiac repair is complete, because new medical challenges keep emerging across the lifespan.
A Less Common Variant on a Different Chromosome
Not every child who looks clinically like DiGeorge syndrome carries the 22q11.2 deletion. A small number of patients have a deletion on a different chromosome altogether, specifically the short arm of chromosome 10. This condition, sometimes called DiGeorge syndrome type 2, produces overlapping features including immune deficiency and heart defects, though the cardiac pattern differs. A review of 19 patients with deletions in the 10p region and congenital heart defects proposed that atrial septal defect, a hole between the upper chambers of the heart, is a common cardiac finding in this variant, in contrast to the outflow tract defects typical of the classic 22q11.2 form.23Wiley Online Library (Clin Genet). Interstitial deletion of 10p and atrial septal defect in DiGeorge 2 syndrome This distinction matters because genetic testing for the 22q11.2 deletion alone could miss these patients.
Passing It On
Most cases of DiGeorge syndrome arise from a new deletion that occurs spontaneously in the embryo; neither parent carries it. But once someone has the deletion, there is a 50 percent chance of passing it to each biological child.24Wiley Online Library. Genetic counseling for the 22q11.2 deletion This has serious implications for adults with DiGeorge syndrome who are starting families. The deletion does not always produce the same set of problems from one generation to the next, so a parent with mild features could have a child with a severe heart defect, or vice versa. Genetic counseling is recommended for all adults with the syndrome who are considering having children, and prenatal testing can identify the deletion early enough in pregnancy to plan for cardiac care at delivery.
The unpredictability of expression also means that some adults carrying the deletion were never diagnosed in childhood, particularly if their heart defect was mild or absent. They may discover their genetic status only after having a child who is diagnosed with a more obvious presentation. Testing parents after a child is diagnosed can sometimes reveal a previously unrecognized case, which in turn opens the door to proactive screening for the parent’s own associated health risks.