chromosomal abnormalities

• What is the study of chromosomes and their abnormalities called?

  Cytogenetics
• What is aneuploidy?

  Abnormal number of chromosomes in a cell
• What is monosomy?

  One less copy of a chromosome pair
• What is trisomy?

  An extra copy of a chromosome
• Why do chromosomal disorders happen?

  Due to ionising radiation, viral infections, and chemical toxins
• What is a metacentric chromosome?

  Centromere lies near the centre of the chromosome
• What is a submetacentric chromosome?

  Centromere is off centre, one arm longer
• What is an acrocentric chromosome?

  Centromere resides near one end
• What is a karyotype?

  Complete set of chromosomes in an individual's cells
• How do scientists identify chromosomes?

  By size, banding pattern, and centromere position
• What is a gene address?

  Combo of numbers and letters on a chromosome
• What is the normal male chromosome pattern?

  46,XY
• What are the two main types of deletions in chromosomal abnormalities?

  Terminal deletion and interstitial deletion
• What is polyploidy?

  Presence of more than one pair of homologous chromosomes
• What is the effect of a centromere deletion in a chromosome?

  The chromosome will not segregate in meiosis or mitosis and will usually be lost
• What is a translocation?

  Unusual rearrangement of chromosomes
• What is a deletion?

  Parts of chromosomes are missing
• What is the frequency of Cri-du-chat syndrome in the population?

  1 in 216,000 people
• What is a duplication?

  Extra parts of chromosomes
• What is an inversion?

  Segment of a chromosome becomes inverted
• What is the significance of the deletion of band p15.3 in chromosome 5 in Cri-du-chat syndrome?

  It leads to symptoms like microcephaly, moon-shaped face, and intellectual disability
• What is triploidy?

  Complete set of extra chromosomes (69)
• What is genomic imprinting?

  Process by which certain genes are branded with parent of origin
• What causes triploidy?

  Dispermy or fertilization of a diploid egg
• What happens to epigenetic markers during gamete formation in genomic imprinting?

  Epigenetic markers are removed, but new markers identifying the gene as coming from either the mother or father are added
• What is diploid?

  Presence of 2 complete sets of chromosomes
• What is the primary symptom of Angelman syndrome?

  Developmental delay
• What is Down syndrome?

  Trisomy of chromosome 21
• What gene is associated with Angelman syndrome?

  UBE3A gene
• What is Edwards syndrome?

  Trisomy of chromosome 18
• What percentage of Prader-Willi syndrome cases are caused by microdeletions of 15q inherited from the father?

  70%
• What is Patau syndrome?

  Trisomy of chromosome 13
• What are the symptoms of Prader-Willi syndrome in infants?

  Severe hypotonia, poor sucking reflex, and poor responsiveness
• What is Turner syndrome?

  45,X (single X chromosome)
• What is the frequency of balanced translocations in humans?

  1 in 500-1000 people
• What is Klinefelter syndrome?

  47,XXY (extra X chromosome)
• What is Jacobs syndrome?

  47,XYY (extra Y chromosome)
• What is the result of a reciprocal translocation in Burkitt’s lymphoma?

  Translocation of the MYC gene on chromosome 8, leading to cancer of lymph nodes
• What is Triple X syndrome?

  47,XXX (extra X chromosome)
• What is the Philadelphia chromosome associated with?

  Chronic myeloid leukemia