chapter 4 pedigree analysis in human genetics powerpoints/chapter4... · chapter 4 human heredity...
TRANSCRIPT
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Chapter 4Pedigree Analysis in Human Genetics
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Mendelian Inheritance in HumansPigmentation Gene and Albinism
Fig. 3.14
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
TwoGenes
Fig. 3.15
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
The Inheritance of Human Traits
Difficulties Long generation time Data must be obtained from
offspring produced Experimental matings are not
possible Limited sample size
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Pedigree Analysis
Pedigree is an orderly presentationof family information
First step in studying the inheritanceof traits
Important in predicting genetic risk May be incomplete due to difficulties
collecting information
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Pedigree Analysis
Construct pedigree using availableinformation
Rule out all patterns of inheritancethat are inconsistent with the data
May not have enough information toidentify the mode of inheritance
Some genetic disorders may havemore than one pattern of inheritance
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Catalogs of Genetic Traits
Figure 4.4
Fig. 4.4
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Autosomal Recessive Traits
For rare traits most affected individualshave unaffected parents
Offspring of two affected individualsare affected
Expressed in males and females equally In rare traits unaffected parents with
affected offspring may be related to eachother
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
PedigreeSymbols
Fig. 3.16
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Proband
First affected familymember who seeksmedical attention for agenetic disorder
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Autosomal recessive
Fig. 4.5
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
1 2
1
2 3 5
32 II
I
III
Rare recessive trait
1 2aa
aa aa
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
1 2
1
2 3 5
32 II
I
III
Rare recessive trait
aa
Aa
1 2
Aa
aa aa
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
1 2
1
2 3 5
32 II
I
III
Rare recessive trait
aa
AaAa
1 2
Aa
aa aa
AA? Aa? Aa?
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Cystic Fibrosis Is an Example of anAutosomal Recessive Trait
Disabling and fataldisorder
Affects sweatglands and glandsthat producemucus anddigestive enzymes
Fig. 4.6
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Molecular Basis for Cystic Fibrosis
Gene located onchromosome 7
Cloned in 1989 (Tsui & Collins)
Fig. 4.8
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Cystic Fibrosis TransmembraneConductance Regulator (CFTR)
CFTR regulatesflow of chlorideions across theplasmamembrane
Reduces fluid inglandularsecretions Fig. 4.9
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Sickle Cell Anemia Is anAutosomal Recessive Trait
Hemoglobin is an oxygen transportmolecule in red blood cells (RBC)
Sickle cell hemoglobin is abnormal andcauses RBCs to become crescent or sickleshaped
RBCs are fragile It is difficult to maintain normal oxygen
carrying capacity
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Sickle Cell Anemia
Many systems are affected Lethal as homozygous recessive Heterozygotes generally unaffected Confers resistance to malaria parasite High frequency in populations where
malaria is found
Fig. 4.11
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Sickle-cell Syndrome
Hb geneHb geneWild-type Hb = A alleleSickle-cell allele Hb = S allele
Wild type AA
SSAffected
S
S
AS
Three kindsof hemoglobins
Carrier
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Carrier (AS)
Polypeptides: , A and S
S
SS
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Normal Carrier Affected Dominance
Hb production AA AS SS Codominant
RBC shape Normal Normal Sickle A -dominantS - recessive
Malaria resistance Normal Resistant Resistant S - dominantA - recessive
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Autosomal Dominant Traits
Heterozygotes and homozygousdominant individuals are affected
Affected offspring have at least oneaffected parent
Equal number of males and females
-
Chapter 4 Human Heredity by Michael Cummings 2006 Brooks/Cole-Thomson Learning
Autosomal Dominant
Fig. 4.12