Reciprocal translocations

Reciprocal translocations involve exchange of chromosomal
segments between two different chromosomes, generated by
the chromosomes breaking and rejoining incorrectly. Balanced
reciprocal translocations are found in one in 500–1000 healthy
people in the population. When an apparently balanced
recriprocal translocation is detected at amniocentesis it is
important to test the parents to see whether one of them
carries the same translocation. If one parent is a carrier, the
translocation in the fetus is unlikely to have any phenotypic
effect. The situation is less certain if neither parent carries the
translocation, since there is some risk of mental disability or
physical effect associated with de novo translocations from
loss or damage to the DNA that cannot be seen on
chromosomal analysis. If the translocation disrupts an
autosomal dominant or X linked gene, it may result in a
specific disease phenotype.