A Phenotypically Normal Homozygous Balanced Reciprocal Translocation Carrier: Report of an Extremely Rare Genetic Occurrence.

Balanced reciprocal translocations (BRT) are relatively common structural chromosomal abnormalities and are typically observed in the heterozygous state. Homozygosity for reciprocal translocations is exceedingly rare, with most documented cases presenting with severe congenital anomalies or developmental delays. To the best of our knowledge, this is the second reported case of a phenotypically normal homozygous BRT carrier born from a natural conception. A 31-year-old female with primary infertility was found to be homozygous for the balanced reciprocal translocation t(11;22)(q23.3;q11.2) during assessment after a failed cycle of in vitro fertilization. Although homozygosity for such translocations can theoretically lead to meiotic errors, gene disruption, or recessive disorders, the proband exhibited a normal phenotype, likely owing to the completely balanced nature of the translocation, making this an exceptionally rare occurrence, challenging assumptions about the consequences of homozygous translocations, and highlighting the need for further research into the specific breakpoint regions.