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

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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=ToNWquoXqJI