Transcript Genetic Diseases & Disorders

Genetic Diseases & Disorders
Biology

Huntington’s disease--lethal genetic
disorder resulting in a breakdown in areas of
the brain. Onset occurs between the ages of
30 and 50 years of age
Huntington’s Disease:






Dominant
Lethal
Affects 30-50
Uncontrolled jerky
movements of head &
limbs
Mental deterioration
Problem: have already
passed it on before being
diagnosed.
Recessive Disorders
 Most Genetic disorders—caused by recessive
alleles

Cystic fibrosis—
Common among white
Americans, causes the
formation and
accumulation of thick
mucous in the lungs
and digestive tract
Cystic Fibrosis:




Recessive
Lethal (late 30’s
currently)
White Americans
Thick mucus in lungs
& digestive tract
making breathing
difficult.

Tay-Sachs disease— Recessive disorder
more common in among Jewish, causes a
build up of lipids in the brain cells
3
4
1
2
III
IV
3
Tay- Sachs







Recessive
Lethal
Begin at age 1, most
die by age 5
Blindness
Loss of movement
Mental retardation
Lipids accumulate in
brain


Phenylketonuria (PKU)—Recessive
disorder in which the body cannot break
down amino acid phenylalanine, causes
severe damage to the central nervous
system and mental retardation
Phenylalanine—used as a sweetener
in diet soda, anyone with PKU cannot
consume diet soda
Phenyl- Ketonuria:






Recessive
Treatable
Norweigan, Suisse
PKU accumulates in central nervous system
Mental retardation
Now tested for shortly after birth
Genetic Disorders

Sickle-cell anemia— a co-dominant trait that
affects the shape of red blood cells

Most common in African Americans
Sickle Cell Anemia

Hemoglobin—protein that carries oxygen in
blood, makes blood red

In homozygous individuals—hemoglobin is defective
and makes blood cells sickle (half moon) shaped


These blood cells—cause slow blood flow, block small
vessels, tissue damage and pain
In heterozygous individuals – both normal and
sickled hemoglobin are produced

They produce enough normal hemoglobin that they do not
have serious health problems
Spleen infected with
sickle cells
Genetic Disorders

Red-green color blindness – a
recessive, sex-linked trait located on
the X chromosome that results in
individuals being unable to see red and
green colors
Genetic Disorders

Hemophilia— a recessive, sex-linked
trait located on the X chromosome that
causes problems with blood clotting

Cuts take a long time to stop bleeding, and
bruising and internal bleeding are
dangerous
•If a male has hemophilia, from which parent did he
inherit the disorder from? ______________
•If a female has hemophilia, from which parent did she
inherit the disorder from? ______________
Hemophilia:




X-linked
Treatable, can be LETHAL
Males
Blood doesn’t Clot
Genetic Disorders

Trisomy 21 (Down Syndrome)—when an individual
has 3 copies of chromosome number 21


Causes some degree of mental retardation in affected
individuals
Can be identified on a karyotype
Downs Syndrome:






3 chromosomes on 21
pair
Not lethal (shorter
lifespan)
Older mothers (over 40)
Mental retardation
Short stature
Other trisomy disorders
are generally fatal https://www.youtube.com/watch?v=ToNWquoX
qJI