Human Diseases
A Systemic Approach
Sixth Edition
Mary Lou Mulvihill
Mark Zelman
Paul Holdaway
Elaine Tompary
Jill Raymond
Chapter 5
Heredity and Disease
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Chapter 5
Heredity and Disease
Multimedia Asset Directory
Slide 10
Slide 24
Sickle Cells
Down Syndrome
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
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Heredity
 DNA – blueprint
 45 chromosomes (genes) (alleles)
 44 autosomes
 2 sex chromosomes: X and Y
 Karyotype
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Human Diseases: A Systemic Approach, 6e
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Genetic Inheritance
 Alleles
– Homozygous
– Heterozygous
– Dominant
– Recessive
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Human Diseases: A Systemic Approach, 6e
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Figure 5-1: Meiosis.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Figure 5-2: Normal human karyotype.
(©Custom Medical Stock Photo.)
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Table 5-1: Hereditary Disease Locations
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Autosomal Dominant
 Transmission of a dominant allele
 50% chance of being affected
 Disease appears in every generation
 Males and females equally being affected
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Figure 5-3: Transmission of autosomal dominant disorders.
(50% chance for an affected child).
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Upper Saddle River, New Jersey 07458
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Click on the screenshot to view an animation showing
sickle cells.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Autosomal Dominant Diseases
 Polydactyly
 Achondroplasia
 Marfan’s syndrome
 Familial hypercholesterolemia
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Figure 5-4: A 12-year old Achondroplastic dwarf. Note the disproportion
of the limbs to the trunk, the curvature of the spine, and the prominent
buttocks.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
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Autosomal Recessive
 Disease manifests when individual is
homozygous for the defective allele
 Parents are carriers; they do not have the
disease
 Child has a 25% chance of being affected
 Recessive allele appears more frequently
in close intermarriages
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Upper Saddle River, New Jersey 07458
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Figure 5-5: Transmission of recessive disorders (25%
chance for an affected child).
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Autosomal Recessive Diseases
 Phenylketonuria
 Galactosemia
 Sickle cell anemia
 Tay-Sachs disease
 Albinism
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Normal red blood cells. (©Phototake NYC.)
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Sickle blood cells. (©Photo Researchers, Inc.)
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Figure 5-6: Enzyme block in phenylketonuria (PKU)
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Sex-Linked Inheritance
 Defective gene on X chromosome
 Defective X on male is unmasked and the
trait is expressed.
 Female is carrier for the disease;
heterozygous
 Male transmits the defective allele to his
daughters.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Upper Saddle River, New Jersey 07458
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Figure 5-7: Transmission of sex-linked disorders.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Autosomal Recessive Diseases
 Color blindness: inability to distinguish
colors
 Hemophilia
 Fragile X syndrome – a break or
weakness on long arm of X chromosome
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Abnormal Chromosome Diseases
 Altered number or structure
 Failure of chromosome to separate during
cell division
 Loss of autosome is usually incompatible
with life
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Down Syndrome
 Caused by the presence of an extra
autosome, nondisjunction
 Results in mental retardation and shorter
life expectancy
 Characteristic appearance: slanted eyes,
extra fold of skin at upper medial corner of
the eye, protrusion of the tongue, short
nose
 Short stature, underdeveloped sex organs
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Click on the screenshot to view a video on the topic of
Down syndrome.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Figure 5-8: Girl with Down syndrome.
(©Beebe / Custom Medical Stock Photo.)
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Familial Disease
 Diseases run in families but means of
inheritance are not understood
 Most likely the effects of several genes
working together
 Examples: diabetes, allergies, familial
polyposis
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
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Upper Saddle River, New Jersey 07458
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Cri Du Chat Syndrome
 Cat-like cry
 Caused by deletion of part of the short arm
of chromosome 5
 Results in an abnormally small head with a
deficiency in cerebral brain tissue
 Widely spaced eyes and mental
retardation
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Sex Anomalies
 Turner’s syndrome: missing sex
chromosome
 Klinefelter’s syndrome: extra sex
chromosome
 Hermaphrodite: has both testes and
ovaries
 Pseudohermaphrodite: has either
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Figure 5-9: A 21-year-old patient with Turner’s syndrome. The chest is
broad and the nipples are small and pale. Pubic hair is totally lacking.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Figure 5-10: A 19-year-old patient with Klinefelter’s syndrome.
Extremities are excessively long, pubic hair is scanty, and genitals
undeveloped. Body proportions resemble those of a eunuch.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Figure 5-11: A 22-year-old patient with pseudohermaphroditism, reared
as a girl because of ambiguous genitalia. Surgery and tissue studies
showed the gonads to be testes.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.