PEDIGREE ANALYSIS

• PEDIGREE ANALYSIS

  • Is a diagram that depicts the biological relationship between an organism and its ancestor. It is used to look at the transmission of genetics disorder.
• Pedigrees use a standard set of symbols to make them easier to understand.

  • MALE – SQUARES
  • FEMALE – CIRCLES
  • PARENTS – CONNECTED BY HORIZONTAL LINE
  • OFFSPRING – VERTICAL LINES
  • SHADED SHAPES – AFFECTED INDIVIDUAL
  • DECEASED – HAS DIAGONAL LINE THROUGH A SYMBOL
  • GENERATION – ROMAN NUMERAS ( I, II, III, IV,……)
• Pedigrees are used to determine how traits are inherited throughout generations – their pattern of inheritance. It is your job to determine the pattern of inheritance
• Autosomal refers to the 1-22 numbered chromosomes as opposed to the sex chromosomes (X and Y)
• Autosomal dominant

  • Autosomal dominant traits pass from one parent onto their child.
  • “Autosomal” means that the gene in question is located on one of the numbered, or nonsex, chromosomes.
  •  “Dominant” means that a single copy of the mutated gene (from one parent) is enough to cause the disorder.
• Autosomal recessive

  • Autosomal recessive traits pass from both parents onto their child.
  • “Autosomal” means that the gene in question is located on one of the numbered, or non-sex, chromosomes.
  • “Recessive” means that a single copy of the mutated gene (from each parent) is enough to cause the disorder
• Sex-linked inheritance involves genes located on (23rd) sex chromosomes

  XX – female

  XY - male
• X-LINKED DOMINANT TRAITS

  • X-linked – gene associated with traits is on the X chromosome
  • Affected males have only affected daughters
  • Affected females can have affected or unaffected offspring (if the mother is heterozygous.
• x-LINKED RECESSIVE TRAITS

  • X-linked – gene associated with traits is on the X chromosome
  • Affected mothers must have affected sons.
  • Two affected parents have only affected offspring
  • Unaffected mother can have affected or unaffected sons (if the mother is heterozygous)
• Y-LINKED TRAITS

  • Y-linked – gene associated with traits is on the Y chromosome.
  • Only males have a Y chromosomes
  • Fathers pass Y chromosome to sons