Genetics and Family History
Kyle J. Betit, 2004
Building Better Pedigrees and Saving Lives
Genealogy and Genetics are two disciplines that are natural partners. Modern genetics testing can advance genealogical research success. Genealogical research can also advance the success of modern genetic disease studies and treatments.
What is Genetics? - Genetics is the branch of biology concerned with heredity and variation.
What is Genealogy? - Genealogy is the study of the history of families, of family relationships, of human pedigrees, of a person’s descent from a particular ancestor or of a person’s progeny. Any genetic study using a pedigree intrinsically involves genealogy.
Genealogists document and construct family genealogies, lineages and relationships usually using available historical records. Pedigrees are the forté of genealogists.
What is DNA? DNA is the acronym for (deoxyribonucleic acid), a molecule that contains the genetic coding. DNA consists of a string of 4 nucleotides: A C G T ( AAACGTGGACGTTA …. )
What is a Gene? A gene is a DNA series that encodes a protein.
Chromosome: DNA in the nucleus is arranged into chromosomes. Each person has 23 pairs total, one of each pair inherited from the mother and the other from the father.
X-Y Chromosomes: The X and Y chromosomes determine gender. A male inherits a Y chromosome from his father and an X chromosome from his mother. A female inherits two X chromosomes.
Nucleus: organelle in a cell that holds almost all of the DNA.
Mitochondria: organelles in a cell that hold a small amount of DNA and are inherited only from the mother.
You can learn more about genetic terminology by visiting the National Human Genome Research Institute (NHGRI) – Talking Glossary of Genetic Terms
Types of Genetic Inheritance
Traits, including genetic disorders, can be inherited in a number of patterns according to what chromosome the trait is encoded on, and whether the trait is dominant or recessive.
Single Gene Disorders
- Autosomal Dominant: one copy of a defective gene is needed (examples: polycystic kidney disease, Huntington’s Disease)
- Autosomal Recessive: two copies of a defective gene are needed (examples: Wilson’s Disease, Cystic Fibrosis)
- X-linked Recessive: only males exhibit the trait because it is encoded on the X chromosome; females can be carriers (example: hemophilia – descendants of Queen Victoria)
Multifactorial Inheritance: multiple gene involvement
Using Genetics to Solve Genealogical Problems
Two major types of tests available at this time:
Paternal Inheritance … Y chromosome testing (men get their Y chromosome from their father)
Maternal Inheritance … mtDNA testing (you get your mitochondrial DNA from your mother)
These tests can add insight to genealogical problems where the historical record is lacking to make connections.
Some Companies Who Conduct Genetic Testing for Genealogical Purposes
- Ancestry DNA: Ancestry.com, Inc., 360 West 4800 North, Provo, UT 84604
- Family Tree DNA: 919 North Loop West, Suite 110, Houston, Texas 77008, USA; Phone: (713) 868-1438; Fax: (832) 201-7147.
- 23 and Me: Rubenstein Communications, 1345 Ave of the Americas, New York, NY 10105
- Oxford Ancestors Ltd: PO Box 288, Kidlington, Oxfordshire OX5 1WG, United Kingdom.
Family Health History
Using Genealogy in your own health interests: family health history
Are you collecting written and oral family health information as you do your genealogy research?
Types of Records Genealogists Use That Could Include Health Information:
- Cemetery records
- Civil registers (vital records)
- Funeral home records
- Hospital records
- Mental institution records
- Military records
- Newspaper notices
- Physicians’ accounts
Visiting Your Doctor with your Genealogy in Hand
As a genealogist, we are in excellent position to provide useful information to our physicians. We can also help other family members to present family health history to physicians to help in check-ups, diagnosis, and treatment.
Genealogy Software and Health Data
Genealogical software programs are available that can store health data.
You can always add health data to the Notes about your ancestors and relatives in your genealogical software. Specific software for family health history: Geneweaver
The below sites will help you find information about genetic disorders, including symptoms, patterns of inheritance, research studies, treatments and management, genetic mapping
- Online Mendelian Inheritance in Man (OMIM) by National Center for Biotechnology Information (NCBI)
- National Organization for Rare Diseases (NORD) – Rare Disease Database
- National Human Genome Research Institute – Specific Genetic Disorders
- National Human Genome Research Institute – Current Clinical Studies
- National Human Genome Research Institute – Genetic and Rare Diseases Information Center (GARD)
- Cyndi's List DNA
Uses of Genealogy in Genetics Research: Genealogy can Help Save Lives
How Does a Disease Trait Genetics Study Progress?
- Condition is identified as genetic and pattern of inheritance found
- Large affected family located to study
- Pedigree built of the extended family
- DNA obtained (blood drawn) from family members (affected and non-affected)
- Search for location of gene: genetic markers associated with specific parts of particular chromosomes tested for LINKAGE with the disease gene present in affected family members.
- Narrowing of location of gene and isolation of gene
- Determination of the protein that is encoded by the gene
- Finding a way to treat the deficiency or problem
- Expansion of pedigree to treat other family members
Some Uses of Genealogy in Genetics Research; Saving Lives
- Building a pedigree
- Expanding a pedigree
- Testing for consanguinity: In some situations, the geneticist may want to know if individuals marrying into a primary pedigree are in fact related in earlier generations. Such information may shed light upon the possible mechanism of the genetic disease (dominant, recessive, complex).
- Finding a founder ancestor: When a disease gene exists in a particular population and appears to have been introduced by one particular individual (such as an immigrant), the genealogist can help identify who the founder may have been.
- Identifying a common ancestor or ancestors among several individuals
- Identifying Descendants and Cousins Who May Be Susceptible: Once a disease gene has been identified within a family, and a common ancestor determined, other descendants can be alerted to the possibility of carrying the gene, and tested to see if they have a particular gene.
- Documenting causes of death or presence of disease in the family
- Researching genetic variability over time
Important Geographical Areas and Groups with Excellent Genealogy Records
- Ashkenazi Jewish
- Quebec, Canada
- Utah (LDS Records & Utah Population Data base)
Ethics and Privacy Concerns
Things to consider with the advent and proliferation of DNA testing.
- A good question: Do you really want to know ? (What if a condition is not yet treatable?)
- How will your insurance company use this information?
- Who else could find out about it?
- What should you share with your family or on the Internet?
- Might people not want to be told they are at risk?
- MedlinePlus: Genetic Testing (NIH)
- Center for Bioethics (University of Minnesota)
- ELSI (Ethics, Legal and Social Issues)
- Human Genome Project
Take Home Message: What Can You Do to Help??
- Record causes of death and other health information from historical records.
- Interview your relatives and record health histories; build a family health history for yourself and your children.
- Contribute your compiled genealogy information so that others can benefit from it.
- Cooperate in genetics studies.
Help index and publish records.
Copy of lecture from "British Isles Family History Society of Greater Ottawa Fall Conference," 18-19 September 2004, Kyle J. Betit