Clinical and Cytogenetic Trends of Down Syndrome: Evidence from Bagalkot District, India

Background: Down syndrome (DS), caused by trisomy of chromosome 21, is the most common chromosomal aneuploidy seen in live births and represents a significant public health concern.Cytogenetic evaluation is essential for accurate diagnosis, clinical management, and genetic counseling.Methods: This retrospective study included 495 clinically suspected cases referred for cytogenetic analysis between 2020 and 2025.Peripheral blood samples were collected after informed consent was obtained.Conventional GTG-banded karyotyping was performed, and Fluorescence in Situ Hybridization (FISH) was used for confirmation.A minimum of 20 metaphases were analyzed for each case, with extended analysis in suspected mosaicism.Results: Out of 495 suspected cases, 32 (6.46%) were confirmed as Down syndrome.Free trisomy 21 was the predominant cytogenetic abnormality, identified in 29 cases (90.6%), while mosaic trisomy 21 was observed in 3 cases (9.3%).The mean maternal age was 31.3 years in free trisomy cases and 26.2 years in mosaic cases, with 36% of mothers aged 35 or older.Cases were reported from both rural and urban areas, with a higher proportion from rural regions.No significant sex predilection was observed.Conclusion: Free trisomy 21 is the most common cytogenetic pattern of Down syndrome in the Bagalkot district.Advanced maternal age remains an important risk factor.Early diagnosis using combined cytogenetic techniques and strengthened prenatal screening programs is essential for effective management and prevention.