Test Details: FISH helps in aneuploidy detection and structural aberration for chromosomes 13, 18, 21, X and Y which account for greater than 90% of chromosomal aberrations. Autosomal monosomies are usually not compatible with life. Autosomal trisomy of chromosomes 13 and 21 are most common trisomy detected in live-births. Trisomy 21 is associated with Down Syndrome and is the single most common known cause of mental retardation. Trisomy 13 is associated with Patau Syndrome. Trisomy 18 is associated with Edward Syndrome. Sex chromosomal aneuploidies including Turner Syndrome (45,X), Klinefelter Syndrome (47,XXY) can also be detected. Structural chromosome rearrangements arise due to chromosome break with subsequent reunion of the wrong segments of the chromosomes. Genetic counselling to couples is essential to explain the recurrence risk and for planning subsequent pregnancies.