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KembaraXtra-Medicine: 22q11.2 Deletion Syndrome
22q11.2 deletion syndrome (22q11.2 DS) is a contiguous gene deletion syndrome caused by a heterozygous deletion on the long arm of chromosome 22 at position q11.2. This deletion typically involves approximately 50 genes, including TBX1, a critical developmental gene involved in cardiac and thymic formation. The syndrome is characterized by a broad and highly variable phenotype, most commonly including congenital heart disease, hypocalcemia, immune dysfunction, palatal abnormalities, renal and skeletal anomalies, gastrointestinal issues, learning difficulties, and psychiatric disorders. It is the most common microdeletion syndrome and most often arises as a de novo event, though it may also be inherited in an autosomal dominant pattern.
The condition has been described under several synonymous diagnoses, including DiGeorge syndrome, velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, Cayler cardiofacial syndrome, and autosomal dominant Opitz G/BBB syndrome. From a coding perspective, it is classified under ICD-10-CM codes Q93.59, Q93.81, Q93.88, and Q93.89, reflecting various chromosomal deletion categories.
Epidemiologically, 22q11.2 deletion syndrome has an estimated incidence and prevalence of approximately 1 in 2,148 individuals. It affects males and females equally and is present at birth, although diagnosis may be delayed or missed in individuals with milder manifestations. Diagnosis tends to occur earlier in patients with congenital heart disease. While it appears more prevalent among individuals of European descent, it occurs across all populations.
Genetically, approximately 85% of affected individuals have the classic 3 Mb deletion at 22q11.2, while around 10% have a smaller nested 1.5 Mb deletion. Because smaller deletions may be missed by fluorescence in situ hybridization (FISH), chromosomal microarray or MLPA is the preferred diagnostic method. About 94% of cases occur de novo due to nonallelic homologous recombination, but when a parent is affected, there is a 50% recurrence risk in each pregnancy. The condition is not associated with advanced maternal age.
Clinically, congenital heart disease is one of the most common and serious manifestations, occurring in approximately 69% of individuals, with about one-third requiring surgical repair. Endocrine abnormalities are present in over half of patients, most notably hypocalcemia due to hypoparathyroidism, as well as thyroid dysfunction, vitamin D deficiency, hypoglycemia, and occasional growth hormone deficiency. Immune dysfunction is seen in the majority of individuals and may include T-cell lymphopenia from thymic hypoplasia, humoral immune deficiencies, recurrent infections, allergies, asthma, and autoimmune conditions.
Otolaryngologic and craniofacial manifestations are frequent and include velopharyngeal insufficiency, submucous cleft palate, bifid uvula, and, less commonly, overt cleft palate or cleft lip. Chronic otitis media, hearing loss, airway abnormalities, obstructive sleep apnea, and characteristic facial features such as hooded eyelids, bulbous nasal tip, and micrognathia are commonly observed. Gastrointestinal involvement often presents as feeding difficulties, dysphagia, gastroesophageal reflux, constipation, and the need for tube feeding in infancy, with occasional structural anomalies such as malrotation or imperforate anus.
Skeletal anomalies occur in roughly half of affected individuals and most commonly involve the cervical spine, sometimes with instability, as well as scoliosis, clubfoot, craniosynostosis, and limb anomalies. Genitourinary findings include renal anomalies, hypospadias, cryptorchidism, and absent or malformed reproductive organs in some patients. Neurologic and developmental manifestations are prominent, with most individuals experiencing learning difficulties, speech and language delay, and mild motor delay. Psychiatric conditions such as ADHD, anxiety, autism spectrum disorder, mood disorders, psychosis, and sleep disturbances are common, particularly in adolescence and adulthood.
Hematologic abnormalities may occur due to deletion of the GP1BB gene, leading to platelet dysfunction and bleeding tendencies. Although malignancy remains uncommon overall, individuals with 22q11.2 deletion syndrome have an increased risk compared with the general population, including leukemias and solid tumors such as Wilms tumor and thyroid carcinoma.
Diagnosis is confirmed by chromosomal microarray or MLPA, with additional baseline evaluation guided by age and clinical findings. Recommended assessments include echocardiography, renal ultrasound, immune studies, calcium and thyroid monitoring, developmental evaluations, and neuropsychological testing. Brain imaging and spinal imaging are reserved for specific clinical indications.
Management is multidisciplinary and lifelong, focusing on early intervention and surveillance. Nonpharmacologic therapy includes early speech therapy beginning in infancy, as well as physical, occupational, educational, and behavioral supports. Medical management may involve calcium and vitamin D supplementation, cardiac medications, endocrine replacement therapy, treatment of immune dysfunction with antibiotics or IVIG, gastrointestinal support, and psychiatric medications when indicated. Surgical interventions may be required for cardiac defects, airway anomalies, gastrointestinal malformations, or palatal abnormalities.
Prognosis varies widely depending on the severity of organ involvement. Most individuals attend mainstream school with additional support, and many achieve varying degrees of independence in adulthood. Morbidity and mortality are increased compared with the general population, with congenital heart disease being the leading cause of death. Long-term follow-up at a specialized 22q center, genetic counseling, and comprehensive family education are essential components of care.
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