Chromosomal Aberrations

• What is a chromosomal disorder?

  A disorder caused by chromosomal changes
• What are chromosomal mutations?

  They are changes in chromosome structure
• What can result from changes in chromosome number or structure?

  Problems in growth, development, and functioning
• What is a karyotype?

  Chromosome constitution of an organism
• How are short arms of chromosomes labeled?

  Short arms are labeled "p"
• How are long arms of chromosomes labeled?

  Long arms are labeled "q"
• What does "proximal" refer to in chromosome structure?

  Segment closest to the centromere
• What does "distal" refer to in chromosome structure?

  Portion farthest from the centromere
• How are chromosome regions labeled?

  Regions are labeled p1, p2, p3, etc.
• What is the designation for the telomere?

  Designated as 'ter'
• What is the designation for the centromere?

  Designated as 'cen'
• How are bands within chromosome regions labeled?

  Sub-bands are labeled p11.1, p12.3, etc.
• What is a dicentric chromosome?

  A chromosome with two centromeres
• What is an acentric chromosome?

  A chromosome with no centromere
• How is chromosome identification performed?

  By size, centromere position, and banding pattern
• What is G banding?

  Chromosomes stained after trypsin digestion
• What do dark bands in G banding represent?

  Condensed chromatin known as G bands
• What are G negative bands?

  Pale bands that are gene-rich
• What causes most chromosomal aberrations?

  Misrepair of broken chromosomes or improper recombination
• What is a constitutional chromosomal abnormality?

  Abnormality present in all body cells
• What is a somatic chromosomal abnormality?

  Abnormality present in certain cells or tissues
• What can a somatic chromosomal abnormality lead to?

  A mosaic individual with different cell lines
• What is a deletion in genetics?

  Missing region of a chromosome
• What is a terminal deletion?

  Deletion at the end of a chromosome
• What is an intercalary deletion?

  Deletion in the middle of a chromosome
• What is the chromosome region deleted in Wolf-Hirschhorn syndrome?

  4p16.3
• What are the main clinical features of Wolf-Hirschhorn syndrome?

  Growth retardation and midline facial defects
• What is the chromosome region deleted in Cri du chat syndrome?

  5p15.2
• What are the main clinical features of Cri du chat syndrome?

  High-pitched cry and severe mental retardation
• What is the chromosome region deleted in Langer-Giedion syndrome?

  8q24.11-q24.13
• What are the main clinical features of Langer-Giedion syndrome?

  Small head and mental retardation
• What is the chromosome region deleted in Williams syndrome?

  7q11.23
• What are the main clinical features of Williams syndrome?

  Cardiac anomalies and characteristic facies
• What is the chromosome region deleted in WAGR syndrome?

  11p13
• What are the main clinical features of WAGR syndrome?

  Kidney tumor and absence of iris
• What is the chromosome region deleted in Prader-Willi syndrome?

  15q11.2
• What are the main clinical features of Prader-Willi syndrome?

  Developmental delay and obesity
• What is the chromosome region deleted in Angelman syndrome?

  15q11.2
• What are the main clinical features of Angelman syndrome?

  Developmental delay and absence of speech
• What is the chromosome region deleted in Miller-Dieker syndrome?

  17p13.3