Cytogenomic characterization of karyotypes with additional autosomal material

Chromosomal rearrangements involving additional material in individuals with phenotypic alterations usually result in partial trisomy, often accompanied by partial monosomy. To characterize chromosomal rearrangements and analyze genomic characteristics in the breakpoint regions in 31 patients with additional material on an autosomal chromosome. Different tests were performed to characterize these patients, including karyotyping, chromosomal microarray analysis (CMA), and fluorescent in situ hybridization (FISH). In silico analyses evaluated A/B chromosomal compartments, segmental duplications, and repetitive elements at breakpoints. The 31 rearrangements resulted in 47 copy number variations (CNVs) and a range of structural aberrations were identified, including six tandem duplications, 19 derivative chromosomes, two intrachromosomal rearrangements, one recombinant, two dicentric chromosomes, and one triplication. A deleted segment was associated with the duplication in 16 of the 19 patients with derivative chromosomes from translocation. Among the trios whose chromosome rearrangement origin could be investigated, 54,5% were de novo, 31,9% were maternally inherited, and 13,6% were paternally inherited from balanced translocations or inversion. Breakpoint analysis revealed that 22 were in the A compartment (euchromatin), 25 were in the B compartment (heterochromatin), and five were in an undefined compartment. Additionally, 14 patients had breakpoints in regions of segmental duplications and repeat elements. Our study found that a deletion accompanied by additional genetic material was present in 51.6% of the patients, uncovering the underlying genetic imbalances. Statistical analyses revealed a positive correlation between chromosome size and the occurrence of CNVs in the rearrangements. Furthermore, no preference was observed for breakpoints occurring in compartments A and B, repetitive elements, or segmental duplications.