1. Genetic diseases are genetic diseases carried on autosomes
Autosomal Diseases
Genetic diseases are genetic diseases carried on autosomes
Autosomes are all of the chromosomes except the X and Y sex chromosomes

2. What is a Pedigree?
A pedigree is a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships. These diagrams make it easier to visualize relationships within families, especially large extended families.
Pedigrees are often used to determine the mode of inheritance (dominant, recessive) of genetic diseases.
Squares represent males Circles represent females.
Horizontal lines linking a male and female represent mating.
Vertical lines extending downward from a couple represent their children.

3. If the purpose of a pedigree is to analyze the pattern of inheritance of a particular trait, it is usual to shade in this trait.
Infected male
In this pedigree: the grandparents
had three children, two boys and
one girl. The daughter married and
Produced two grandchildren, both
boys.
The grandfather has the trait. The daughter is a carrier. One of the grandsons has the trait.

4. Types of Inheritance
There are four types of inheritance patterns that we will be analyzing:
1. autosomal dominant
2. autosomal recessive
3. X – linked dominant
4. X- linked recessive

5. Autosomal Recessive Traits
In order to express the trait, two recessive alleles must be present.
What would be the genotype of an individual with an autosomal recessive trait? (A = dominant) aa
What would be the genotype of an individual without the autosomal recessive trait?
AA or Aa
Aa – called a Carrier because they carry the recessive allele and can pass it on to offspring, but they do not express the trait.

6. Autosomal Recessive Traits
Heterozygotes are Carriers with a normal phenotype.
Most affected children have normal parents. (Aa x Aa)
Two affected parents will always produce an affected child. (aa x aa)
Two unaffected parents will not produce affected children unless both are Carriers. (AA x AA, AA x Aa)
Affected individuals with homozygous unaffected mates will have unaffected children. (aa x AA)
Close relatives who reproduce are more likely to have affected children.
Both males and females are affected with equal frequency.
Pedigrees show both male and female carriers.

7. How does it happen? Affected Genotype: aa

8. Albinism
Defect of melanin production that results in little or no color in the skin, hair, and eyes

9. Albinism

10. Albinism

11. Cystic Fibrosis
Disease that causes the body to produce unusually thick, sticky mucus that:
Clogs the lungs and leads to lung infections
Obstructs the pancreas
Stops natural enzymes from helping the body break down and absorb food

12. Red blood cells carry oxygen.
Sickle Cell Anemia
Caused by an abnormal hemoglobin shape which causes the red blood cells to have a crescent shape.
Red blood cells carry oxygen.

13. Autosomal Recessive Pedigree
Draw a Pedigree showing a cross between Heterozygous parents that have 2 boys and 2 girls. (Show all possibilities)
Genotypes of Affected and Unaffected:
AA=Unaffected Aa=Carrier, Unaffected aa=Affected Aa AA aa

14. Autosomal Dominant Traits
If dominant allele is present on the autosome, then the individual will express the trait.
What would be the genotype of an individual with an autosomal dominant trait?
AA and Aa (Heterozygotes are affected)
What would be the genotype of an individual without the autosomal dominant trait? aa

15. Autosomal Dominant Traits
Heterozygotes are affected
Affected children usually have affected parents.
Two affected parents can produce an unaffected child. (Aa x Aa)
Two unaffected parents will not produce affected children. (aa x aa)
Both males and females are affected with equal frequency.
Pedigrees show no Carriers.

16. How does it happen? Affected Genotype: HH or Hh

17. Huntington’s Disease
Causes the break down of brain cells, (neurons) in certain areas of the brain.
Causes uncontrolled movements, loss of intellectual faculties, and emotional disturbance.

19. Progeria
Drastic premature aging, rare, die by age Symptoms include limited growth, alopecia, small face and jaw, wrinkled skin, atherosclerosis, and cardiovascular problems but mental development not affected.

20. Autosomal Dominant Pedigree
Draw a Pedigree showing a cross between Heterozygous parents that have 2 boys and 2 girls. (Show all possibilities)
Genotypes of Affected and Unaffected:
AA and Aa = Affected aa = Unaffected Aa AA aa

21. Sex-Linked Traits
Sex-linked traits are produced by genes only on the X chromosome.
They can be Dominant or Recessive.
What would be the genotypes of a male and female that have a Sex-linked Dominant trait and do not express the trait?
Expresses Trait: Male - XA Y Female - XA XA or XA Xa
No Expression: Male - Xa Y Female - Xa Xa
What would be the genotypes of a male and female that have a Sex-linked Recessive trait and do not express the trait?
Expresses Trait: Male - Xa Y Female - Xa Xa
No Expression: Male - XA Y Female - XA XA or XA Xa
(Carrier)
Most Sex-linked traits are Recessive!

22. Sex-Linked Recessive Traits
More males than females are affected.
An affected son can have parents who have the normal phenotype. (XAY x XAXa)
For a daughter to have the trait, her father must also have it. Her mother must have it or be a carrier (XaY, XaXa, XAXa)
The trait often skips a generation from the grandfather to the grandson.
If a woman has the trait (XaXa), all of her sons will be affected.
Pedigrees show only female carriers but no male carriers.

23. How does it happen? Affected Genotypes: XbXb XbY

24. Inability to see colors in the normal way
Color Blindness
Inability to see colors in the normal way

26. Inability of the blood to clot properly
Hemophilia
Inability of the blood to clot properly

27. How does it happen? Affected Genotypes: XhXh XhY

28. Sex-Linked Recessive Pedigree
Draw a Pedigree showing a cross between a normal male and a Carrier Female.
Genotypes of Parents:
Male = Xh Y Female = XH Xh
XRY
XrY
XRXR
XRXr
XRXr

29. What does a pedigree look like?
What is a pedigree?
Definition: a graphic representation of genetic inheritance used by geneticists to map genetic traits
What does a pedigree look like?
Affected
Generations in separate rows indicated by Roman numerals (I, II, III…)
Individuals within one generation indicated by Arabic numerals (1, 2, 3…)
Parents connected by horizontal lines
Offspring connected by vertical lines
Female
Male
Carrier
Unaffected
Dead

30. What if the trait is sex-linked? How can you tell?
Answer: Most affected individuals are males

31. Let’s try one…Is this sex-linked or not?
Answer: Yes

32. Mutations Chromosomal Mutations
1. Caused by a change in structure or number of chromosomes
2. Detected by KARYOTYPING which matches homologous chromosomes in a diploid (2N) cell by:
Size of chromosome
Length of chromatid arms
3. Centromere location

33. Karyotype

34. Down Syndrome

35. Klinefelter syndrome Cause by nondisjunction Symptoms:
too many chromosomes: 3 sex chromosomes = XXY; the sex is male; resulting in 47 total chromosomes
Symptoms:
Underdeveloped male sex organs
Sterility
May have feminine body parts

37. Turner Syndrome Cause by nondisjunction Symptoms:
not enough chromosomes; 1 sex chromosome = XO the sex is female; resulting in 45 total chromosomes
Symptoms:
Females are usually short
Sex organs may not develop
Sterility

38. Turner Syndrome