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Genetics and Public Health in the 21st Century



CHAPTER 10
TABLES


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Table 1. Malaria, TB, and HIV/AIDS: transmission, prevention and risk groups

Disease Pathogen (type) Transmission Prevention At-risk population
Malaria Plasmodium  spp. (parasite) Vector (Anopheline mosquito), blood Prevent vector contact, chemoprophylaxis Children and pregnant women in endemic areas. All age groups in nonendemic areas
Tuberculosis (TB) Mycobacterium tuberculosis (acid-fast bacillus) Aerosol Reduce exposure, BCG vaccine, chemoprophylaxis Children, adults, immunocompromised persons
HIV/AIDS Human immuno- deficiency virus type 1 (HIV-1)(lentivirus) Sexual contact, blood or blood products Reduce exposure, chemoprophylaxis Fetus/neonate (vertical transmission), adolescents, adults

Table 2. Host genes, impact on infectious diseases, and population frequency

Disease Gene/ genotype Chromo-some location Impact of gene/genotype on infectious diseases Population frequency *References
Resis-tance Susceptibility Disease outcome
Malaria
Duffy antigen negative
1p22.1 and 1q12-q21
+
 
Total protection against P.vivax infection
Africans near 100%
Absent in Caucasians
and Mongolians
27, 28
Sickle-cell trait
(Hb AS)
11
+
> 90% protection against falciparum cerebral
malaria, severe anemia and death
Kinshasa, Zaire 26%
Ibadan, Nigeria 24%
Accra, Ghana 8%
Kampala, Uganda 19%
Kisumu, Kenya 25%
31-34
α-thalassaemia
16pter-p13.3
+
Reduction of risk of severe malaria to 0.40
in homozygotes, and to 0.66 in heterozygotes
Reduction in risk of hospital admissions due to
other infections 0.36 in homozygotes, and
0.63 in heterozygotes
Tharu, Nepal 80%
Vanuatu 8-38%
Papua New Guinea
4-38%

36, 37

38, 39

β-thalassaemia
11p15
+
Partial protection against severe disease
in Liberia (P.Falciparum)

Variable frequencies
in Mediterranean,
Middle east, south-
east Asia, and Africa

40
Melanesian
ovalocytosis
17q21-q22
+
Band 3 deletion not found in patients with
cerebral malaria in Papua New Guinea.
Protection against severe disease
Up to 30% in aboriginal
population in south-east
Asia and Pacific islands
Absent in Africans
41, 42
G6PD deficiency
Xq28
+
46-58% reduction in severe malaria for both
male hemizygotes and female heterozygotes
in the Gambia
Female heterozygotes
in Gambia 13.7%
in Kenya 27.3%
Male hemizygotes
in Gambia 5.9%
in Kenya 18.8%
43
HLA-B53
6p21.3
+
Partial protection (4-50%) against cerebral
malaria and anemia
Nigerians 40%
Gambians 25%
Zambians 21%
Zimbabweans 16%
South Africans 2%
Caucasians and
Orientals 0-1%
35
DRB1*1302
6p21.3
+
Protection against severe malaria anemia
Northern Italian
2.97%
**
TNF-2 homo-zygote
[a poly-morphism
in the promoter
region of TNF-a
gene (-308)]
6p21.3-
q21.1
+
7- fold increased risk of death and neuro-
logic sequealae due to cerebral malaria
Gambians,
TNF-2 allele
frequency 0.16
45
ICAM-1
19p13.3-
p13.2
+
2-fold increased susceptibility to
cerebral malaria
Kenya >30%
Caucasians rare
or absent
46

* The references are for the population frequencies. The references for the disease outcome are already included in the text
** HLA 1998 Gjertson DW and Terasaki PL ed, American Society for Histocompatibility and Immunogenetics (ASHI)

Table 2 (cont'). Host genes, impact on infectious diseases, and population frequency

Disease Gene/ genotype Chromo-some location Impact of gene/genotype on infectious diseases Population frequency *References
Resistance Susceptibility Disease outcome
TB
Tay-Sachs(TS)
gene
15q23-q24
?
No evidence of protection against TB
TS carriers ~ 4%
60, 61
HLA-DR2
6p21.3
+
DR2 associated with TB severity

DRB1*1501/ DRB1*1502
South African Blacks
6.4/0. 0
Black Americans 8.6/0.8
Japanese (Wajin) 6.8/9.2
Highlanders (Papua New
Guinea) 14.7/4.5
French 7.1/0.3
German 7.8/1.1
Italian 5.5/2.2
USA White 9. 9/0.7
Canadian 10. 9/0.6
Indian 12/11.9

***
†DRB1 *1501
+
DRB1*1501 and DRB1*1502 both
associated with severity and radiogra-
phic extent of clinical TB
†DRB1*1502
+
DRB1*1501 and DRB1*1502 both
associated with drug failure in TB
treatment
HLA-DQB1 *0503
6
+
Associated with clinical TB
Cambodians <1%
Caucasian US 1.7%

50

**

NRAMP-1
2q35
+
4-fold increased risk of TB in
persons heterozygous for INTR4
and 3’UTR polymorphisms
Allelic frequency in
Gambians 3%
17
IFN-γ R
6q23-q24
+
Both associated with non-TB
mycobacterial disease.
no published data
78, 79
IL12R (IL12B1)
19p13.1
+
Only IFN-γ R is associated with
adverse events post BCG vaccination
Vitamin D
receptor (VDR)
12q12-q14
+
tt homozygosity associated with
increased risk of TB disease
t allele frequency
in Caucasian 45%
****

†DRB1*1501 and 1502 are HLA-DR genotypes that type serologically as HLA-DR2
*** Proceedings of the 11th International Histocompatibility Workshop and Conference. Yokohama, Japan 1991
**** Hill AVS, Ruwende C, Corrah T et al. Association of immunognetic variants with susceptibility to tuberculosis in West Africa.
Q J Med. 1996; 89: 868


Table 2 (cont'). Host genes, impact on infectious diseases, and population frequency

Disease Gene/ genotype Chromo-some location Impact of gene/genotype on infectious diseases Population frequency *References
Resis-tance Susceptibility Disease outcome
HIV
HLA class I/II
6p21.3
+
+
Faster progression associated with
alleles B7, B27, DR7,
haplotype A1-B8-DR3, and
homozygosity status
Reduction of vertical transmission with
class I disparity
Caucasians
10% B7, 4% B27,
13% DR7
3% haplotype
A1-B8-DR3
90
TAP (often
in combination
with HLA)
6p21
+
Influence on progression
no data on
frequency
90
Δ 32 CCR5
3p21
+

Homozygosity associated with resistance
to HIV infection

Heterozygosity associated with delayed
progression to AIDS

Homozygosity
Caucasians <1%
Heterozygosity
Caucasians10-20%
African Americans
6%
Hispanics 7%
Native Americans
13%
20
CCR2-V64I
3p21
+
Delayed-progression to AIDS
Caucasians 10%
Asians 25%
20, 80
SDF1-3’A
10q11.1
?
Influence on progression
Caucasians 21%
Hispanics 16%
African Americans
6%
Asians 26%
95
TNF-α
6p21.3
?
Long-term non progression
no data on frequency
99

Table 3. From Host Genes to Public Health Actions: Prevention and Control of Infectious Diseases

Prevention Strategy for Infectious Diseases Incorporation of Host Genetic Information
Surveillance and Response --------> Existing Surveillance Systems
Data collection by HuGE Net
Population based surveys of the prevalence of genetics factors
Surveillance systems of infectious diseases in Local and State
Departments of Health and by Federal Government Agencies
Applied Research ---------------------> Genetic Studies, Genetic Engineering
Association and linkage studies, assessment of the interactions
between genetics and environmental factors
Clinical trials, assessment of the efficacy of or adverse outcomes
to vaccines, antibiotics, gene therapy or other interventions
Assessment of new technology
Behavioral sciences and program evaluation
Infrastructure and Training---------> Partnership and Information Dissemination
Funding, laboratory support, training of public health
professionals, global surveillance network development
Information exchange, education of the lay public, and advocacy groups
Prevention and Control--------------> Reinforcement of Classical Measures
Primary, secondary, and tertiary prevention
 
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