Test Details: Karyotyping helps to detect chromosomal aberrations which can result from either a variation in chromosome number or from structural rearrangement. Numerical aberrations or aneuploidies may be in the form of loss or gain of chromosomes. Autosomal monosomies are usually not compatible with life. Autosomal trisomy of chromosome 13, 18 and 21 are most common trisomy detected in live-births. Trisomy 21 is associated with Down Syndrome and is the single most common cause of mental retardation. Trisomy 18 is associated with Edward Syndrome. Trisomy 13 is associated with Patau Syndrome. The common sex chromosomal aneuploidies include Turner Syndrome (45,X) and Klinefelter Syndrome (47,XXY). Structural chromosome rearrangements arise due to chromosome break with subsequent reunion of the wrong segments of chromosomes. Unbalanced translocation may lead to significant clinical consequences in the form of dysmorphic features and mental sub normality in the child. Balanced translocation may have no phenotypic abnormalities with normal mental and physical fitness in the child. Genetic counselling to couples is essential to explain the recurrence risk and for planning subsequent pregnancies.