Early childhood onset of high-grade atrioventricular block in Hunter syndrome

Area of Science:

• Cardiology
• Genetics
• Pediatrics

Background:

• Mucopolysaccharidoses (MPS) are a group of genetic disorders characterized by the accumulation of glycosaminoglycans.
• Cardiac involvement, particularly valve pathology, is a common and significant complication in various MPS syndromes.
• Hunter syndrome (MPS II) is an X-linked MPS with diverse clinical manifestations.

Observation:

• A 3-year-old boy with diagnosed Hunter syndrome presented with various degrees of atrioventricular (AV) block.
• This represents an unusual early-onset, high-grade conduction abnormality in the context of Hunter syndrome.
• No prior reports documented such early-onset high-grade AV block in pediatric Hunter syndrome patients.

Findings:

• The case demonstrates that significant cardiac conduction abnormalities, including high-grade atrioventricular block, can manifest early in childhood in Hunter syndrome.
• Cardiac valve pathology is the most recognized cardiac issue, but conduction defects are also a critical concern.
• Routine electrocardiographic monitoring is crucial for identifying these potentially asymptomatic conduction abnormalities.

Implications:

• Early and routine cardiac screening for conduction abnormalities is vital for all patients diagnosed with mucopolysaccharidoses syndromes.
• Prompt identification of atrioventricular block allows for timely intervention and management, potentially preventing severe outcomes.
• This case underscores the importance of comprehensive cardiac surveillance beyond valve pathology in managing Hunter syndrome and related MPS disorders.