Which chromosomal abnormalities are routinely considered when CHD is detected?

• A. Trisomy 21 alone
• B. Trisomy 18 and Trisomy 13
• C. 22q11.2 deletion only
• D. 22q11.2 deletion, Trisomy 18, Trisomy 13, and sometimes Trisomy 21

Answer: (D)

When a fetus or newborn has congenital heart disease, clinicians actively look for chromosomal abnormalities because heart defects frequently occur as part of genetic syndromes. The abnormalities routinely considered are the 22q11.2 deletion (DiGeorge syndrome) and the common aneuploidies Trisomy 18 and Trisomy 13, with Trisomy 21 (Down syndrome) also being a frequent associated condition. 22q11.2 deletion is particularly linked to conotruncal and great-artery anomalies, while Trisomies 18 and 13 commonly present with CHD alongside other major anomalies; Trisomy 21 is frequently associated with CHD as well. Because identifying these conditions influences prognosis, counseling, and management, genetic testing is typically offered when CHD is detected, often incorporating microarray or targeted testing for 22q11.2 in addition to standard karyotyping for the trisomies. This combination explains why all four are routinely considered.