Autosomal dominant and recessive are mutations that occur
on any chromosome, not just the X and Y sex chromosomes. Autosomal dominant genetic
illnesses just need one copy of the defective gene to be afflicted. There are no
carriers of autosomal dominant diseases.
Autosomal
recessive requires two copies of the defect to affect the individual. Persons with one
copy of the defective gene typically do not suffer the effects of the defect but are
carriers, meaning they can pass on the defective gene to their offspring. Males and
female offspring are affected equally by autosomal
defects.
X-linked genetic disorders occur on the X sex
gene. Males (XY) pass on their Y chromosome to their sons and their X chromosomes to
their daughters. Once again dominant means only one copy of the genetic defect is needed
to affect the individual, making the daughter of an affected male affected as well.
X-linked recessive requires two copies of the defective chromosome, making the daughter
of an affected male a carrier unless she inherits the same X-linked defect from her
mother's X chromosome. Because males do not pass on X-linked chromosomes to their sons,
this type of genetic illness (X-linked recessive and dominant) cannot be passed on to
male offspring.
Because a male parent only passes on their
Y chromosome to their male offspring, a defect of a y-linked chromosome would result in
an affected male offspring.
While males have mitochondrial
DNA, only female pass that DNA onto their offspring. A male with a genetic disorder
linked to mitochondrial DNA would not pass the disorder onto his male child because he
does not pass on any mitochondrial DNA to his offspring.
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