American researchers working on Hypoplastic Left Heart Syndrome (HLHS), a severe cardiovascular malformation that is difficult to treat and is often fatal, have found that the condition is caused primarily by genetic factors.
The researchers found that the malformation has high heritability, suggesting that families with a child with HLHS carry a significant recurrence risk.
“Our study demonstrates that HLHS has high heritability, suggesting it is caused almost entirely by genetic effects instead of environmental factors, and that families with a child with HLHS carry a significant recurrence risk of HLHS or related heart defects. This should be considered by physicians when counselling parents to ensure they are aware of potential risks,” said the lead author of the study, Robert B. Hinton, Jr., M.D., a physician.
The study conducted at Cincinnati Children’s Hospital Medical Center included 38 family-based test groups with a history of HLHS.
The authors of the study found that 55 percent of those families had one or more blood relative with HLHS or an associated heart defect. Of 193 blood relatives evaluated between the ages of 3 days and 74 years, 21.4 percent had HLHS or associated heart defects.
In families where one child already had HLHS, the risk of HLHS recurring in a sibling was 8 percent while the risk of a sibling having an HLHS-associated cardiovascular defect was 22 percent. In families where a child and one parent had HLHS, the recurrence risk increased dramatically to 21 percent for recurring HLHS and 25 percent for an associated defect.
All participants were evaluated using echocardiography to determine specific phenotype, or the visible heart characteristics and defects found among the different family test groups. During those examinations researchers diagnosed 12 new cases of associated defects among relatives of HLHS patients.