CGH, FISH techniques effective for postmortem analysis of fetuses, infants with congenital anomalies

New techniques to detect chromosomal abnormalities can offer a higher degree of accuracy. Chromosomal abnormalities are a well-known cause of multiple congenital anomalies, and conventional methods of culture analysis have proven unsuccessful in 10% to 40% of cases. Comparative genomic hybridization (CGH) and fluorescent in situ hybridization (FISH) techniques were tested and found successful by analyzing tissue from children who had multiple congenital anomalies.

The May issue of the journal Pediatric and Developmental Pathology reports results from this study, which examined the feasibility of CGH and FISH in retrospective genetic analysis to detect chromosomal abnormalities.

CGH is a new molecular technique that allows the entire genome to be analyzed in frozen or paraffin-embedded tissue. It is based on DNA rather than metaphase cultures like traditional methods of analysis. The FISH technique can be used to confirm the CGH findings or detect abnormalities that CGH could not. FISH analysis is specifically directed at certain chromosomal regions.

This study used DNA from the postmortem tissue of 92 patients, most of whom had multiple congenital anomalies. Four normal patients were included as controls. In many of the cases, the karotype was already known, and the testing confirmed the success of the CGH technique. In 40 patients, the karotype was unknown but identified by CGH in 90% of the cases. Among these, one additional chromosomal aberration, that of Turner syndrome, was identified.

CGH offered an interpretable result in 93% of the cases tested. The authors concluded that "these techniques are valuable additional tools in the postmortem analysis of fetuses and infants with (multiple) congenital anomalies and can be considered as an expansion of the diagnostic armamentarium of the pathologist."