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DiGeorge syndrome, also known as 22q11.2 deletion syndrome, is a multisystem developmental disorder caused by microdeletion of chromosome 22q11.2. It primarily affects structures derived from the 3rd and 4th pharyngeal pouches, resulting in cardiac, craniofacial, immunological, endocrine, and neurodevelopmental abnormalities.
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https://www.youtube.com/watch?v=7DhBLgh0kds
CATCH-22: Mnemonic for features
| Letter | Feature |
|---|---|
| C | Cardiac defects (especially conotruncal) |
| A | Abnormal facies |
| T | Thymic hypoplasia/aplasia → immune deficiency |
| C | Cleft palate or velopharyngeal insufficiency |
| H | Hypocalcemia (due to parathyroid hypoplasia) |
| 22 | Chromosome 22q11.2 microdeletion |
| Domain | Feature |
|---|---|
| C: Cardiac | Primarily conotruncal defects: |
| • Interrupted aortic arch (Type B) | |
| • Truncus arteriosus | |
| • Tetralogy of Fallot (ToF) | |
| • Ventricular septal defect | |
| • Aortic arch anomalies | |
| A: Craniofacial (abnormal facies) | **• Hypertelorism |
| • Short palpebral fissures | |
| • Small chin (micrognathia) | |
| • Low-set, posteriorly rotated ears | |
| • Nasal bridge flattening** | |
| T: Thymic hypoplasia/aplasia | • Reduced or absent thymic shadow on CXR |
| • T-cell immunodeficiency → recurrent infections (especially viral/fungal) | |
| **C: Palatal anomalies | |
| (cleft palate)** | • Cleft palate |
| • Submucosal cleft | |
| • Velopharyngeal insufficiency → nasal speech, feeding difficulty | |
| H: ‣ | • Due to parathyroid hypoplasia |
| • Presents with seizures, tetany in neonates | |
| Neurological/Developmental | • Intellectual disability (mild to moderate) |
| • ADHD, autism spectrum disorders | |
| • Psychiatric illness (e.g., schizophrenia in adolescence) |
| Modality | Imaging features |
|---|---|
| CXR | • Absent thymic shadow in neonates |
| • Cardiomegaly if associated CHD | |
| Echo | First-line for evaluating conotruncal cardiac defects |
| • Truncus arteriosus, IAA (especially Type B), ToF, VSD, right arch | |
| CTA/MRA | Precise aortic arch anatomy (e.g., IAA Type B, aberrant subclavian) |
| • Aortic arch interruption, aberrant subclavian arteries, cervical aortic arch | |
| Brain MR | For developmental delay, seizures |
| • Mild cortical atrophy, corpus callosal thinning (non-specific) |