Cytogenetics or Chromosomal studies is an important laboratory procedure for the diagnosis and treatment of patients with developmental delay, mental retardation, unexplained major or minor malformations, abnormalities of sexual development, infertility, recurrent pregnancy loss, bad obstetric history, prenatal diagnosis and cancer.
Cytogenetic testing is done to obtain chromosomes from different types of cells such as lymphocytes, amniocytes, bone marrow etc. For this procedure cells need to be dividing either on their own or after stimulation. The chromosomes in the metaphase stage of cell division give the best chromosome morphology for analysis. Giemsa-banded chromosomes are arranged in pairs and groups to be represented as a Karyotype. Karyotypes are assessed to identify both structural and numerical abnormalities.
47,XX +21 indicates Female Karyotype with Trisomy 21/Down’s Syndrome
46, XX, t(4;6)(q35; q22) indicates a Female Karyotype with translocation between long arm of chromosome 4 and 6