1. Human Diseases A Systemic Approach Sixth Edition
Mary Lou Mulvihill
Mark Zelman
Paul Holdaway
Elaine Tompary
Jill Raymond
Chapter 5 Heredity and Disease

2. Chapter 5 Heredity and Disease
Slide 10 Sickle Cells
Slide 24 Down Syndrome
Copyright ©2006 by Prentice-Hall, Inc. Upper Saddle River, New Jersey All rights reserved.
Mulvihill, Zelman, Holdaway, Tompary, and Raymond Human Diseases: A Systemic Approach, 6e

3. Heredity DNA – blueprint 46 chromosomes (genes) (alleles) 44 autosomes
2 sex chromosomes: X and Y
Karyotype

4. Genetic Inheritance
Alleles
Homozygous
Heterozygous
Dominant
Recessive

5. Figure 5-1: Meiosis.

6. Figure 5-2: Normal human karyotype. (©Custom Medical Stock Photo.)

7. Table 5-1: Hereditary Disease Locations

8. Autosomal Dominant Transmission of a dominant allele
50% chance of being affected
Disease appears in every generation
Males and females equally being affected

9. Figure 5-3: Transmission of autosomal dominant disorders
Figure 5-3: Transmission of autosomal dominant disorders. (50% chance for an affected child).

10. Click on the screenshot to view an animation showing sickle cells.
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11. Autosomal Dominant Diseases
Polydactyly
Achondroplasia
Marfan’s syndrome
Familial hypercholesterolemia

12. Figure 5-4: A 12-year old Achondroplastic dwarf
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.

13. 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

14. Figure 5-5: Transmission of recessive disorders (25% chance for an affected child).

15. Autosomal Recessive Diseases
Phenylketonuria
Galactosemia
Sickle cell anemia
Tay-Sachs disease
Albinism

16. Normal red blood cells. (©Phototake NYC.)

17. Sickle blood cells. (©Photo Researchers, Inc.)

18. Figure 5-6: Enzyme block in phenylketonuria (PKU)

19. Autosomal Recessive Diseases
Color blindness: inability to distinguish colors
Hemophilia
Fragile X syndrome – a break or weakness on long arm of X chromosome

20. 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.

21. Figure 5-7: Transmission of sex-linked disorders.

22. Abnormal Chromosome Diseases
Altered number or structure
Failure of chromosome to separate during cell division
Loss of autosome is usually incompatible with life

23. Patau Syndrome +13

25. 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

26. Click on the screenshot to view a video on the topic of Down syndrome.
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27. Figure 5-8: Girl with Down syndrome
Figure 5-8: Girl with Down syndrome. (©Beebe / Custom Medical Stock Photo.)

28. 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

29. 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

30. Sex Anomalies Turner’s syndrome: missing sex chromosome
Klinefelter’s syndrome: extra sex chromosome
Hermaphrodite: has both testes and ovaries
Pseudohermaphrodite: has either

31. Figure 5-9: A 21-year-old patient with Turner’s syndrome
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.

32. Figure 5-10: A 19-year-old patient with Klinefelter’s syndrome
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.

33. 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.