From the Research
The risk of having a second child with Down syndrome depends primarily on maternal age and the specific type of Down syndrome in their first child, with a recurrence risk of approximately 1% above the maternal age-related risk for standard trisomy 21. For most families with a child who has standard trisomy 21 (which accounts for about 95% of Down syndrome cases), the recurrence risk is approximately 1% above the maternal age-related risk, as stated in 1. The maternal age-related risk is a significant factor, with the risk increasing from about 1 in 1,000 at age 30 to about 1 in 100 by age 40, as mentioned in 2. If genetic testing reveals their child has translocation Down syndrome (about 4% of cases), the recurrence risk could be significantly higher (10-15%) if one parent carries a balanced translocation.
Key Factors to Consider
- Maternal age: The risk of Down syndrome increases with maternal age, as noted in 3.
- Type of Down syndrome: The specific type of Down syndrome in the first child can impact the recurrence risk, as discussed in 4.
- Genetic testing: Genetic testing can help determine the type of Down syndrome and identify potential recurrence risks, as explained in 5.
Recommendations
- I recommend the couple meet with a genetic counselor who can review their specific situation, including the exact type of Down syndrome their child has and the mother's current age.
- The counselor can provide personalized risk assessment and discuss available prenatal testing options, such as non-invasive prenatal testing (NIPT) or diagnostic tests like amniocentesis or chorionic villus sampling (CVS), as mentioned in 1 and 5.
- These tests can help the family make informed decisions based on their personal values and circumstances, as noted in 2 and 4.