The inheritance of genes located in the sex chromosomes
Sex-linked gene
Gene located on a sex chromosome
x linked Dominant
50% chance of inheriting the trait/mutation/disorder (Dobyns et al., 2004)
If the father is affected, all of the females will be affected
If the mother is affected, 50% chance that the son or daughter is affected
x linked Dominant Disorders
Vitamin D resistant rickets (soft bones)
Fragile X Syndrome
x linked Recessive
A female parent possessing one X-linked recessive mutation is considered a carrier
If a father has an X-linked recessive disorder, he will pass the affected X chromosome to all of his daughters (carriers)
y-linked
holandric (only present in Y chromosome) inheritance
Manifestation of a phenotypic trait by an allele (or gene) on the Y chromosome
Y-linked traits are passed only from father to son, with no genetic recombination occurring
y linked Disorder
Y chromosome infertility
Affects the production of sperm and causes male infertility
Sperm cells that are abnormally shaped or that do not move properly
Sex-influenced traits
Traits that are phenotypically expressed depending on whether the individual is male or female
Sex-influenced traits
Baldness or Female sterility in Drosophila (in insects)
Pedigree chart
A diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next
Presentation of family information summarized in a chart using a standardized set of symbols where squares represent males and circles represent females
