After this class you will be able to:
- Explain a) what genetics and genomics are, and b) how they are relevant for public health, giving at least 3 concrete examples.
- Evaluate a laboratory test used in public health practice in terms of the ACCE Framework and apply this to at least one genetic test.
- Increase your score on the Genetics Awareness checklist.
How it relates to VCU MPH Competencies: 1A(1,3,6) 1C(1.2.6.7) 1D(1,5,8) 1F(all)
This class on genetics and public health will use a case-based approach to help you learn about contemporary issues at the intersection of public health and genetics. Our overall goal is to encourage you to recognize the genetic aspect of public health problems. Just as learning about infectious organisms two centuries ago altered public health practices, from sanitation to immunizations, new knowledge and technologies in genetics are altering and will continue to impact public health practices. Genetic information influences health and disease across the life span, from preconceptional genetic counseling and fortification of flours with folate to improvements in our understanding of causes of death and disability, from newborn hearing screening where over half of congenital hearing loss is genetic to recognition of the familial risk factors inherent in, for example, Alzheimer disease, cancer, coronary artery disease and stroke.
Is closing summer camps for children with muscular dystrophy because of their apparent susceptibility to the H1N1 virus a modern day John Snow water pump story?
Refs:
Host Genetic Background Strongly Influences the Response to Influenza A Virus Infections
PLoS ONE. 2009; 4(3): e4857. Published online 2009 March 18.
Barkha Srivastava1, Paulina Błaz_ejewska1, Manuela Heßmann1, Dunja Bruder2, Robert Geffers3, Susanne Mauel4, Achim D. Gruber4, Klaus Schughart1*
1 Department of Experimental Mouse Genetics, Helmholtz Centre for Infection Research & University of Veterinary Medicine Hannover, Braunschweig, Germany, 2 Research Group Immunoregulation, Helmholtz Centre for Infection Research, Braunschweig, Germany, 3 Gene Expression Analysis, Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany, 4 Department of Veterinary Pathology, Faculty of Veterinary Medicine, Freie Universita¨t Berlin, Berlin, Germany
The genetic make-up of the host has a major influence on its response to combat pathogens. For influenza A virus, several single gene mutations have been described which contribute to survival, the immune response and clearance of the pathogen by the host organism. Here, we have studied the influence of the genetic background to influenza A H1N1 (PR8) and H7N7 (SC35M) viruses. The seven inbred laboratory strains of mice analyzed exhibited different weight loss kinetics and survival rates after infection with PR8. Two strains in particular, DBA/2J and A/J, showed very high susceptibility to viral infections compared to all other strains. The LD50 to the influenza virus PR8 in DBA/2J mice was more than 1000-fold lower than in C57BL/6J mice. High susceptibility in DBA/2J mice showed a higher viral load in their lungs, elevated expression of cytokines and chemokines, and a more severe and extended lung pathology compared to infected C57BL/6J mice. These findings indicate a major contribution of the genetic background of the host to influenza A virus infections. The overall response in highly susceptible DBA/2J mice resembled the pathology described for infections with the highly virulent influenza H1N1-1918 and newly emerged H5N1 viruses.
Your Challenge:
Imagine you have graduated with your MPH. It is your first week as Director of Public Health Genetics for Virginia. This class is going to walk you through 3 public health genetic issues that arrive on your desk that first week. How will you handle them?
Before class:
- Complete the Genetics Awareness checklist. How prepared are you for the Director of Public Health Genetics job?
- Read about the role of Genetics in the Provision of Essential Public Health Services: Wing G. & Watts C. AJPH April 2007, V94 #4
- Review the following web site - Advocating for Folic Acid: A Guide for Health Professionals (www.folicacid.net)
- Read about genetic association tests:
- Read through the background information below
Background Information:
Key Words
- Autosomal dominant– genes that exhibit their effects when only one altered copy is present (e.g. neurofibromatosis, Huntington disease, many cancer susceptibility genes like BRCA1/2)
- Autosomal recessive-- genes that exhibit their effects when two altered copies are present (e.g. sickle cell anemia, cystic fibrosis
- Birth defect – any morphological abnormality present at birth (e.g. cleft palate, neural tube defect)
- Cancer cluster – a greater-than-expected number of cancer cases that occurs within a group of people in a geographic area over a period of time
- Children with special health care needs – includes all children who have or are at risk for chronic physical, developmental, behavioral, or emotional conditions and who also require health and related services of a type or amount beyond that required by children generally. It is estimated that 18 million children in the United States have these special health care needs (Maternal and Child Health Bureau)
- Congenital anomaly - a defect that is present at birth (considered synonymous to “birth defect”)
- Folate – a vitamin that plays a vital role in DNA metabolism
- Genetic susceptibility – a tendency to a disease or health alteration based on genetic changes
- Genetics - the scientific study of heredity, how particular qualities or traits are transmitted from parents to offspring.
- Genomics – the study of genes and their function
- Human Genome Project- the 13-year (1990-1993) federal project to map the total human DNA sequence of ~30,000 genes
- Multifactorial – caused by a combination of genetic and environmental factors
- Polymorphism – DNA variation that is not yet known to have clinical significance
- Teratogen – any agent that increases the incidence of congenital malformations (e.g. thalidomide, isotretinoin)
Concepts:
- It is estimated that influences on health and disease are 40% behavioral, 30% genetic, 20% environmental, and 10% health care.
- The human body contains ~25,000 genes typically packaged for cell division in 46 chromosomes.
- Genes help determine our responsiveness to environmental changes. Genes also interact with one another. Differing genes, polymorphisms, and genetic susceptibilities show varied responses and interactions.
- The causes of birth defects include chromosomal alterations, Mendelian conditions, teratogens, and multifactorial conditions.
- 3-4% of children are born with a birth defect.
- 239,900 children in Virginia are estimated to have special health care needs.
- The Centers for Disease Control (CDC) recommends that all women who may become pregnant take 0.4 mg. of folic acid daily at least one month prior to conception. USPSTF (United States Preventive Services Task Force) has recommended 0.4-0.8 mg. daily (www.ahrq.gov/clinic/uspstf09/folicacid/folicacidrs.pdf )
- The burden of developmental/intellectual disabilities may be reduced through genetic understanding and services.
- Family history is increasingly being valued as a public health tool to screen for common diseases.
- “We are all diseased, just not diagnosed yet.” Francis Collins MD PhD, Medical Geneticist, former Director, National Institute for Human Genome Research, nominee for NIH director
An ongoing challenge for public health personnel is to incorporate current understanding of the science of health and disease in effective and ethical public health measures. Your understanding of the relevance of the genetic components of your family health history to your own health and your willingness to think about these complex issues for society and public health are both part of your legacy. Think genetically.
The National Coalition for Health Professional Education in Genetics (www.nchpeg.org), a coalition of more than 120 health professional organizations, and the CDC (http://www.CDC.gov/genomics/training/competencies/default.html) have developed a set of competencies in genetics for health professionals and for the public health workforce. Review these competencies and continue to reflect upon them as you go through your MPH program.
The following have been identified as public health functions relevant to genetics:
- public health assessment
- evaluation of genetic testing
- development, implementation, and evaluation of population interventions; and
- communication and information dissemination.
Critical issues include:
- partnerships and coordination
- ethical, legal and social issues; and
- education and training.
[See: Genetics and Public Health in the 21st Century (Muin Khoury, Wylie Burke, Elizabeth J Thomson (eds.), New York, Oxford University Press, 2000) is a comprehensive monograph about using genetic information to improve health and human disease.]
The following web sites may be useful for your further study.
- Genetic Alliance
- GeneReviews
- Genetics Home Reference
- www.marchofdimes.com
- National Human Genome Research Institute
- National Coalition for Health Professional Education in Genetics
- Office of Genetics and Disease Prevention
- Online Mendelian Inheritance in Man
- U.S. Surgeon General's Family History Initiative
Also, scan the following:
- Home Test Kit causes controversy
- Can Family History be Useful?
- Marfan's Syndrome (June 08)
- Flour Fortification with Folic Acid
- Genomics & Primary Care (Also applicable to the session on aging.)
- The Genie is out (Editorial from NEJM, Jan. 2008)
- Pharmacogenomics — Ready for Prime Time? (Editorial NEJM Mar 2008)