Pericentric and paracentric inversions.

Pericentric and Paracentric Inversions

Chromosome inversions are structural abnormalities in which a segment of the chromosome is broken and reinserted in an inverted direction (180 degrees):

• Pericentric Inversion: The inverted segment includes the centromere. There is a risk of giving rise to unbalanced gametes with duplications and partial deletions after meiotic crossing-over, which can cause abortions or affectively dysmorphic offspring.
• Paracentric Inversion: The inverted segment does not include the centromere. It produces digocentric and acentric gametes after recombination, which are usually unviable, reducing the possibility of living unbalanced offspring but increasing infertility.