Summary GTS161 theme 5 notes

Theme 5
Defini&ons
• Pedigree - pictorial representa&on of a family history, family tree that outlines the
inheritance of one or more trait
• Proband - person from whom the pedigree is ini&ated




Autosomal recessive traits
• in both sexes with = frequency
• skip genera&ons
• affected offspring to unaffected parents
• Appears more frequently among the children of consanguineous marriages
Autosomal dominant
• both sexes with = frequency
• does not skip genera&ons
• unaffected parents do not transmit the trait
X-linked recessive
• more males than females affected
• affected sons born to unaffected mothers
• skips genera&on
• half of carrier mother sons ara affected
• NEVER passed from father to son
• daughters of affected fathers are carriers
X-linked dominant
• more females than males affected
• does not skip genera&ons
• affected sons = affected mother
• affected daughters = affected mother or father
• affected fathers to all daughters
Y-linked traits
• ONLY males
• father to all sons
• does not skip genera&ons
Twins
• Dizygo&c twins - non iden&cal twins (2 separate eggs are fer&lized by 2 different
sperm)(50% of genes alike)