Transcript Aim: What areGenetic Conditions?

List at least 3 genetic conditions you know of.
Why do you think they are genetic conditions?
What are genetic Diseases?
 A genetic disease is any
disease that is caused by
an abnormality in an
individual's genome.
 Can range from small
mutations in a single base
to huge chromosome
abnormality such as extra
or missing chromosomes
 Some are inherited
others are caused by
acquired mutations
Categorizing Genetic Conditions
If we categorize genetic conditions by the way they are
inherited there are 5 main types:
 Autosomal Dominant
 Autosomal Recessive
 Sex-Linked
 Codominant
 Mitochondrial
Autosomal dominant
 One mutated copy of the
gene is enough for a
person to be affected by
an autosomal dominant
disorder.
 Autosomal dominant
disorders tend to occur
in every generation of an
affected family.
 Example: Huntington
disease
Autosomal recessive
 Two mutated copies of the
gene are present in a
person has an autosomal
recessive disorder.
 An affected person usually
has unaffected parents who
each carry a single copy of
the mutated gene
 Typically not seen in every
generation of an affected
family.
 Example: Sickle cell
Disease
Sex-linked
 Includes X-
linked
dominant and
recessive
conditions
 Affected gene is
on sex
chromosome.
 Usually affects
one gender
more than the
other
 Example: Color
Blindness
Codominant
 Two different versions
(alleles) of a gene can be
expressed, and each
version makes a slightly
different protein.
 Both alleles influence
the genetic trait or
determine the
characteristics of the
genetic condition
 Example: ABO blood
group, alpha-1
antitrypsin deficiency
Mitochondrial
 Also known as maternal




inheritance.
Applies to genes in
mitochondrial DNA.
Only females can pass on
mitochondrial mutations
to their children
Can show up in every
generation of a family
Affect both males and
females
Identify the following diseases by
how they are inherited.
Just write down the number of the
condition and the type of condition
1. Tay-Sachs Disease (chromosome
15)
 Progressive nervous system degeneration.
 A child is deaf and blind by one or two years-
progressive mental retardation, loss of muscular
control; usually die at age three or four.
 Most carriers choose to avoid the birth of a child
because there is no treatment.
 Both Parents need to pass on the gene for the
child to have the condition.
2. Amyotrophic lateral sclerosis
(ALS, Lou Gehrig=s disease)
(chromosome 21)
Affects 1 in 100,000 people worldwide, but only 10% of
the cases are inherited. The other 90% are probably
environmentally induced (don=t know cause).
 Fatal degenerative nerve disease.
 Stiffening and weakening of the legs and arms,
become quadriplegic, die as respiratory muscles
become paralyzed.
 One copy of the gene is enough to have the
condition
3. Androgenic alopecia
(AKA) Male Pattern Baldness
 Classic androgenic hair loss in males begins above
the temples and vertex of the scalp. As it progresses, a
rim of hair at the sides and rear of the head remains.
 The gene responsible is on the X chromosome
 Affects males more than Females because Females
need 2 copies of the gene to show symptoms'
4. Leber hereditary optic
neuropathy?
 Although this condition usually begins in a person's
teens or twenties, rare cases may appear in early
childhood or later in adulthood.
 Can only be passed down by mothers
 Gene responsible is found in the mitochondria
5. Alpha-1 antitrypsin deficiency?
 Alpha-1 antitrypsin deficiency is an inherited disorder
that may cause lung disease and liver disease.
 About 10 percent of infants with alpha-1 antitrypsin
deficiency develop liver disease, which often causes
yellowing of the skin and whites of the eyes (jaundice).
 Two different versions of the gene may be active
(expressed), and both versions contribute to the
genetic trait.
Answers
1.
2.
3.
4.
5.
Autosomal Recessive
Autosomal Dominant
Sex Linked
Maternal or Mitochondrial
Codominant