DiGeorge Syndrome Prevalence in TOF with Absent Pulmonary Valve
Approximately 10% of patients with tetralogy of Fallot and absent pulmonary valve syndrome (TOF-APVS) have DiGeorge (22q11.2 deletion) syndrome.
Specific Prevalence Data
The available evidence provides a clear answer for this rare variant:
- In a UK national registry study of 98 children with TOF-APVS, exactly 10% had DiGeorge syndrome 1
- This is notably lower than the 15% prevalence seen in standard tetralogy of Fallot without the absent pulmonary valve variant 2, 3
Context: DiGeorge Syndrome in Conotruncal Defects
To understand this finding, it's important to recognize the broader pattern:
- Standard TOF has a 15% prevalence of 22q11.2 deletion 2, 3
- TOF is listed as a common cardiac finding in DiGeorge syndrome by the 2019 AHA/ACC guidelines 4
- The highest prevalence occurs with interrupted aortic arch type B, where 22q11.2 deletion approaches 75% 4
- Overall, 25-75% of patients with DiGeorge syndrome have congenital heart disease, depending on the population studied 4
Clinical Implications
Genetic screening for 22q11.2 deletion should still be performed in all patients with TOF-APVS despite the lower prevalence 2:
- Presence of the deletion significantly impacts mortality risk (worse survival in adults with TOF and 22q11.2DS) 5
- Affects reproductive counseling (50% transmission risk to offspring) 2
- Requires multisystem surveillance for thyroid disease, hypocalcemia, immunodeficiency, and psychiatric disorders 6
- Influences perioperative management (increased complications though not necessarily mortality) 7
Important Caveat
The 10% figure comes from a single national registry study 1, and the rarity of TOF-APVS surviving to adulthood means this estimate has limited precision. However, this represents the best available data from a modern, multi-center cohort and is consistent with the observation that absent pulmonary valve syndrome can occur without 22q11.2 deletion 8.