RESUMEN
Introduction: Klinefelter Syndrome is one of most common sex chromosomal abnormality in males with incidenceof 1 in 600 live births. Fluorescence in situ hybridization (FISH) is a powerful molecular cytogenetic techniquewhich allows rapid detection of aneuploidies on interphase cells and metaphase spreads along with conventionalGTG banding technique.Aims and objectives: To evaluate application of karyotyping and FISH as important diagnostic tool in diagnosisKlinefelter Syndrome.Materials and Methods: A retrospective study was conducted on 44 patients who were referred for karyotypingand counselling with suspected Klinefelter Syndrome and hypogonadism to Division of Human Genetics,Department of Anatomy, St. John’s Medical College, Bangalore from January 2014 to October 2017. Chromosomalpreparations were done using the peripheral lymphocyte culture method followed by GTG banding technique,automated photography and karyotyping.FISH was performed with dual colour X/Y probes once abnormality was detected using GTG banding technique.Results: Out of 44 patients, 9 had typical karyotype of Klinefelter syndrome (47,XXY) and Four had variants ofKlinefelter syndromeConclusion: We can conclude that cytogenetic analysis forms important investigation in diagnosis , treatmentand fertility status in patients with Klinefelter syndrome.