Transcript Human Genetic Disorders

Human Genetic
Disorders
Their symptoms…
Albinism
inherit genes that do not make the
proper amounts of pigment
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Albinism
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Homozygous
recessive
Cystic Fibrosis (CF)
homozygous recessive trait on
(autosomes)
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Sickle Cell Anemia
(substitution of adenine for thymine)
homozygous recessive
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Sickle Cell Anemia
Polydactyly
(autosomal) homozygous recessive
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Polydactyly
Webbing of Fingers
(autosomal)
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Webbing of Toes
(autosomal)
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Klinefelters Syndrome XXY
Nondisjunction
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Tallness with extra long arms and legs
Abnormal body proportions (long legs, short trunk)
Enlarged breasts
Lack of facial and body hair
Small firm testes
Small penis
Lack of ability to produce sperm
Diminished sex drive
Sexual dysfunction
Learning disabilities
Personality impairment
Klinefelters syndrome presenting “leg
ulcers”
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1/50 –1/1000 are born
With KS
Extra X chr. #47
Due to anaphase lag
(fails to separate)
Chronic venus
Insufficiencies
Obesity
Reduced testosterone
Therapy (cause)
Turners syndrome X
Nondisjunction
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Turner syndrome is a birth defect caused
by the absence of an X chromosome in
some or all cells of a female, which inhibits
sexual development and usually causes
infertility.
MONOSOMY – zygote with 45
chromosomes
Continue…
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In Turner syndrome, an error occurring very
early in development results in an abnormal
number and arrangement of chromosomes.
Most commonly, an individual with Turner
syndrome will be born with 45
chromosomes in each cell rather than 46.
The missing chromosome is an X
chromosome. The affected person is
always female
Mosaics…
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More than half of all girls with Turner
syndrome are mosaics, which means that
the mutation occurs in some but not all
cells of their body. Therefore, Turner
syndrome can vary in severity. The fewer
the affected cells, the milder the disease
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1 / 2,500 female births have turners
syndrome
Symptoms of Turner Syndrome
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short stature
webbed skin of the neck
abnormal eye features (drooping eyelids)
abnormal bone development, such as a "shield-shaped," broad flat
chest
absent or retarded development of secondary sexual characteristics
that normally appear at puberty, including sparse pubic hair and
small breasts
coarctation (narrowing) of the aorta
bicuspid aortic valve
infertility
dry eyes
absence of menstruation
Webbed Neck
Webbed Neck
Turner’s syndrome
Mom and her daughter with Turner’s
Syndrome
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Down’s Syndrome
nondisjunction
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Children with Down’s syndrome
Trisomy 21
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Who gets dwarfism and bone
dysplasias?
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Bone dysplasias and dwarfism are rare. The most
common type of dwarfism (achondroplasia) occurs in
one in 15,000 children.
A defective gene that stops bone from growing in the
usual way causes most bone dysplasias. Sometimes
this gene is passed on from a parent to a child (genetic).
Much more often, though, the condition arises from a
new change in the gene (spontaneous genetic
mutation), and the baby is the first in her family to be
affected.
Achondroplasia
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Autosomal
dominant
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Thumbelina has dwarfism
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Huntington’s Disease (HD)
(autosomal dominant allele)
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Symptoms of HD
 Mild
forgetfulness and irritability
 Appears between 30-40 yrs. Old
 Loss of muscle control
 Uncontrollable physical spasms
 Severe mental illness
 Eventually death
Phenylketonura (PKU)
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Autosomal homozygous dominant
Lacking amino acid phenylalanine
Loss of motor skills, mental dibilitation
Treatment: diet change, restricted diet
Tay Sach
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Autosomal recessive
Normal 1st 6 months
Deterioration of nerve cells
Treatment: enzyme replacement therapy
Cri DU Chat Syndrome
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Missing piece of chromosome #5
Most are not inheritted
High pitch cry that sounds like a cat
Intellectual disability and delayed
development
Small head size
Treatment: behavior modified programs
Marfan’s Syndrome
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Dominant
Defective connective tissue, tall, long limbs,
thin fingers (heart valves and aorta)
Treatment: as problems arise
Muscular Dystrophy
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Genetic or malnurishment (prenatal)
Progressive skeletal weakness
Hemophilia
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X linked disorder
Lack of blood clotting factor (platelets)
Treatment: transfusions platelets
Vocab…
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Pleiotropy = one gene for many
characteristics. Ex: sickle cell
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Polygenic = many genes for one
characteristic. Ex: skin color, height