Down’s Syndrome Presented with Transmission of Maternal Translocation of 2; 21 Chromosomes. A Case Report

Background: Down's syndrome is a genetic condition marked by distinctive physical characteristics and some degree of cognitive impairment. Down's syndrome is mostly caused by trisomy of chromosome 21, while chromosome translocations are also frequent. Objective: To evaluate a rare 2;21 translocation in the proband's family that was associated with Down syndrome. Methods: Chromosomal analysis was carried out using the G-banding technique and traditional peripheral lymphocyte culture. Case: The proband was a 9 months baby boy of non-consanguineous parents. The doctors clinically diagnosed him as having Down's syndrome with all typical features. The proband was found to have trisomy 21 associated with a 2;21 translocation inherited from his mother because his mother has the same type of translocation without any phenotypic features. Maternal age at the time of the study was 35 years and first pregnancy ended in stillbirth at 26th weeks of gestation, the proband was the second issue. His maternal aunt and cousin brother both had the same type of translocation. In chromosomal analysis, the proband's father and uncle had normal genotypic distribution. The current example was a Down's syndrome case with one normal 21 no chromosome and one Reciprocal translocation t (2;21). Conclusion: The present case of Down’s syndrome occurs due to reciprocal translocation (2;21) probably has arisen by familial transmission. Once an imbalanced translocation in the fetus/child has been found, the prenatal cytogenetic analysis is critical for the next pregnancies. Bangladesh Medical Res Counc Bull 2023; 49(2): 143-147