American University of Armenia Biological Anthropology Questions

1. What is the HLA complex? Why is it so variable in our species?

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2. Discuss the terms ‘biocultural evolution’, ‘balanced polymorphism’, heterozygote advantage’ using sickle cell anemia as an example?

3. What is the Bombay Blood type- and what is its relationship to the ABO system?

4. Using the ABO blood system as an example- discuss the terms antigen and antibody.

Blood Groups and Proteins 1
Definitions
• Antibodies (Immunoglobulins) – protein
molecules that attach to foreign substances
rendering them harmless
• Antigens – foreign substances that stimulate
the synthesis of antibodies
• Agglutination – attachment of antibodies +
antigens
ABO(H) Blood Group
• ABO Locus on chromosome #9
• Antibodies present without previous exposure
• At least 7 exons long
• Single nucleotide deletion in exon 6 = O Blood
• 7 substitutions in Exons 6 and 7 determine
differences between A and B
• Actually 4 Alleles – A1, A2 (1/4 antigens), B, O(H)
ABO Blood Group
H Antigen
• Found on virtually all RBCs
• Chromosome #19 – One antigen (H and h alleles)
• Building block for the ABO system
• Deficiency = Bombay blood type (hh) –
transfusion from normal “O” causes severe
reaction
• If no H – then cannot have A or B
• 1 of 8,000 in Taiwan, 1 of 10,000 in India, and 1
per million in Europe
ABH Blood Group
Paternity Determination Complications
with Bombay
Child is Ohh – Therefore Alan is Father
ABO Blood Groups
• Three alleles not evenly distributed around
world
• O allele is the most common throughout the
world, followed by A, B is rarest.
• Interesting patterns in Americas, Australia and
Europe.
A Allele Distribution
B Allele Distribution
ABO and Diseases
• Cholera – O = increased risk of infection and
stronger symptoms
• Syphilis – O blood = more resistant
• Plague (Anti O) –presence of H antigen
protects
• Smallpox – Anti A (O and B do better).
• Mosquitoes prefer O
• Infantile diarrhea – worse in A and B
Differential Fertility
• O women < fertility with A or B men • OO women x AO or BO man > expected # of
OO children
– prezygotic – Vaginal antibodies react with A or B
sperm)
– Postzygotic – increased spontaneous abortion
when maternal and fetal blood types are
incompatible
– Should lead to eventual fixation of O
Rhesus Factor
• Three loci (CcDdEe) on (Chromosome #1)
• Dd most important (D = +, d = -)
• Antibodies NOT present without exposure
• Hemolytic disease of newborn
• Generally Rh- high in Europeans (40%)
• Africans Rh- (25 %)
• Native Americans and Native Australians
almost 100% Rh+
MNS System
• Chromosome #4
• Two codominant alleles (MN) (GPA gene)
• Closely linked S (Ss) (GPB gene)
• Passed on as haplotye (MS, Ms, NS, Ns)
• High levels of MS and Ms in Native Americans
• High frequencies of N in Native Australians and
New Guineans
• Total lack of S among Native Australians, but high
amongst Native New Guineans
• Potential link to Malaria and influenza
Duffy System
• Chromosome #1
• Three alleles – Fya Fyb, Fyo
• Phenotypes Fy(a+ b+), Fy(a-b+), Fy(a+b-), Fy(ab-)
• Fy(a-b-) = 100% Africans – may be
hypersensitive to blood transfusion of duffy +
blood (a or b)
• Fy (a-b-) protected from malaria disease (not
infection)
Hemoglobin Variants
Hemoglobin
• Large complex molecule
• Four long amino acid
chains
• Each chain
encompasses heme
group = which binds to
oxygen transporting it
around body and
releasing as needed
Sickle Cell Anemia
• Single point mutation altered and less
efficient form of
hemoglobin
• Potentially lethal
especially during
strenuous exercise (life
expectancy = 40 years
in USA, lower in Africa)
• 100,000 deaths per year
world wide
Genetics
• Two alleles – HbA (normal), HbS (sickle) –
Incomplete dominance
• HbA, HbA = normal RBCs
• HbS, HbS = Sickle cell disease
• HbA, HbS = carrier (variable effects)
• Two carriers have 25% chance of having child
with SCD = 1/400 births in African Americans
Sickle Cell Anemia
Physiological effects
Sickle Cell/Malaria Association
• Heterozygote advantage – cells less able to
support malarial parasite growth, longer life
span, higher fertility
• Balanced Polymorphism
• Biocultural Evolution
Malaria
• Lethal, mosquito-borne
• Plasmodium spp. (4 species in humans P.
vivax, P. ovale, P. malariae, and P. falciparum)
• Anopheles mosquitos
• Endemic to most tropical areas
• Approx. 2 million deaths worldwide annually
Malaria Life Cycle
Sickle Cell Video
Type E Hemoglobin
• Mutation in the β globin gene
• Third most common Hb variant
(HbA>HbS>HbE)
• Highest frequencies in South and Southeast
Asia (Hb E approaches 60% in many regions of
Thailand, Laos and Cambodia)
• HbE, HbE ≠ severe anemia
• HbA, HbE – resistant to malaria
Thalassemia
• Complete synthesis of either α or β chain
disrupted
• Frame shifts mutations – entire sequence
changes, chain shorter or absent entirely
• Severe anemia, 100,000 childhood deaths per
year
Thalassemia major
• β Thalassema
• Autosomal dominant on chromosome #11
• Decreases or halts synthesis of beta-Hb chain
• Unstable RBCs (lethal in homozygotes)
• Multiple mutation sites (some more lethal
than others), vary by region
Alpha Thalassemia
• Deficiency of alpha-Hb chain
• Two loci on chromosome #16
• Mild-lethal symptoms
• Frequencies follow distribution of malaria
• New Guinea =- 22-68% on coast (malaria
present) versus 2-5% in highlands (malaria not
present)
Sardinia
• 1.5 million people
• Isolated villages
• Genetic markers vary by
area
• Malaria major problem
in some areas prior to
1944
Decline of Thalassemia
Sardinia
• Inverse relationship of
G6PD and Thalassemia
with altitude
• Villages not fitting
pattern – recent
immigrants
Genetics of African Americans
• Reduction in frequency of HbS (5% versus 15%
in Africa).
• Reduction of malarial pressure – and genetic
admixture
• Areas with lowest rates of admixture and
highest historical rates of malaria show
highest HbS rates today
Gullah Islands
• Coastal South Carolina
• Most recent persistence
of malaria
• Cultural isolation
• Highest rates of HbS
and (16%)
• Video
Beta Globin RFLPS
African Hb Haplotypes in the New World
HAPLOTY JAMAICA UNITED
PE
STATES
BRAZIL
SENEGAL 10
15
1
BENIN
72
62
26
BANTU
(CAR)
17
18
73
Origins of Slaves Taken From Africa
Variability in HB Haplotypes
• Haplotypes vary in
severity of HbS.
• Senegal – retention of
more HbF – prevents
cell distortion
• Benin – less HbF – SCD
more severe.
ANTH 311 Fall 2022: Test #2 Review Sheet
Blood Proteins
Antibodies, antigens, agglutination
ABO blood groups
H – antigen – Bombay blood type
Distribution of different Alleles
Differential fertility of women with O blood
ABO and diseases
Rhesus factor – genetics, problems with childbirth, distribution
MNS system
Duffy system
Serum Proteins
IgG Immunoglobulins
Haptoglobins – Hp1, Hp2
Transferrins – TfC, TfD, TfB
Lipoproteins – APO A, APO C and APO E
G6PD Deficiency/Favism
Sex-linked (X) males vs females, genotypes, GdA-, Gdmed – distribution
Favism and Malaria
Why G6PD so prevalent?
HLA Definitions
HLA – Human Leukocyte Antigens (MHC), immunity
HLA Genes
Variation in HLA Haplotypes – hypervariable
Linkage Disequlibrium
HLA and Disease
Link between HLA and Disease
Ankylosing Spondilitis
Mate Choice
Hemoglobin Variants
Structure and function of hemoglobin
Sickle Cell Anemia – genetics, distribution, association with malaria, balanced polymorphism,
biocultural evolution (slash and burn agriculture)
Type E hemoglobin – genetics, distribution, relationship to malaria
Thalassemia – major and alpha, genetics, distribution, relationship to malaria
Malaria – life cycle
Sardinia – malaria and Thalassemia
African Americans and Sickle Cell, Gullah Islands
Hemoglobin haplotypes and slave trade
Lactose, Ear Wax and Taste
Lactose Tolerance – genetics, distribution, biocultural evolution
Cerumen, two types – genetics, distribution, relationship to body odor, relationship to breast
cancer
PTC tasting – threshold levels, genetics, amino acid polymorphisms, distribution, evolutionary
significance
Asparagus and urine odor – genetics
Cilantro and soap taste – distribution

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