Molecular cytogenetic identification of small supernumerary marker chromosomes using chromosome microarray analysis

Area of Science:

• Genetics
• Prenatal Diagnostics
• Cytogenetics

Background:

• Small supernumerary marker chromosomes (sSMCs) present diagnostic challenges.
• Accurate characterization of sSMCs is crucial for genetic counseling and clinical management.

Purpose of the Study:

• To assess the utility of chromosomal microarray analysis (CMA) for identifying the origin and structure of sSMCs.
• To explore genotype-phenotype correlations associated with sSMCs.
• To evaluate CMA's feasibility in prenatal and postnatal settings.

Main Methods:

• Banding cytogenetics was used to identify 33 cases with sSMCs.
• Chromosomal microarray analysis (CMA) was performed on 29 cases.
• Fluorescence in situ hybridization (FISH) was used for comparison in two cases.

Main Results:

• CMA successfully identified the chromosomal origins of 22 out of 29 cases.
• Pathogenic copy number variations (PCNVs) were detected in 16 cases.
• CMA results indicating pathogenic abnormalities influenced pregnancy termination rates.

Conclusions:

• CMA combined with cytogenetic analysis is highly effective for sSMC identification.
• Further studies with larger cohorts are needed to establish robust sSMC-related genotype-phenotype correlations.