Prevalence of chromosomal abnormalities and 22q11.2 deletion in conotruncal and non-conotruncal antenatally diagnosed congenital heart diseases in a Chinese population.

INTRODUCTION: The aim of the present study was to calculate the prevalence of chromosomal abnormalities among antenatally diagnosed congenital heart diseases (CHDs), and the prevalence of 22q11.2 deletion in those with conotruncal CHDs versus isolated non-conotruncal CHDs.

METHODS: All patients with antenatal ultrasound finding of fetal CHDs in two obstetric units in a 5-year period were retrospectively reviewed. Detected CHDs were classified as conotruncal if the malformation involved either the aortic outflow tract or the pulmonary outflow tract; otherwise they were classified as non-conotruncal. Karyotyping, fluorescence in situ hybridisation for 22q11.2 deletion (22q11FISH), and array comparative genomic hybridisation (aCGH) results were retrieved from patient medical records. The primary outcome was prevalence of chromosomal abnormalities in CHDs. The secondary outcomes were prevalence of 22q11.2 deletion and its prevalence in conotruncal versus non-conotruncal CHDs.

RESULTS: A total of 254 Chinese patients were diagnosed to have fetal CHDs. In all, 50 (19.7%) were found to have chromosomal abnormalities with seven (2.8%) patients having 22q11.2 deletion, of whom all seven had conotruncal CHDs and none had non-conotruncal CHDs (P<0.05). Conventional karyotyping detected 35 (70%) cases of the chromosomal abnormalities. The 22q11FISH detected three cases of 22q11.2 deletion; aCGH was performed to detect four cases of 22q11.2 deletion and eight other cases of copy number variations.

CONCLUSION: Our results suggest that invasive testing for karyotyping is recommended for fetal CHDs. Although the prevalence of 22q11.2 deletion was low, testing for 22q11.2 deletion should be offered for conotruncal CHDs.