Episode 048-May 17, 2016
In this episode, Muriel Normand continues her discussion of dominant genetic diseases. If you have not listened to episode #47 yet, I’d suggest you do so before continuing with this episode because Muriel introduced us to Genetics 101, explained the founder effect, and walked us through an explanation of OPMD, or oculopharyngeal muscular dystrophy.
In this episode, she continues explaining other dominant genetic diseases, as well as common recessive, mtDNA, and x-linked diseases. We also go into more detail about the BALSAC database.
French-Canadian Genetic Diseases-part 2
In this episode, Muriel and I discussed the following:
- Types of diseases
- Especially in dominant diseases, a person can carry the trait but not express it. So, like OPMD, it can skip a generation.
- mtDNA diseases are passed from mother to child.
- Recessive diseases are only expressed if both parents carry the trait.
- X-linked diseases are passed on by mothers and show up in males because that is the only X-chromosome the male child gets, and it is dominant over the Y.
Terms you need to understand
- Genotype: your genetic make-up as distinguished from your physical appearance
- Phenotype: what you look like
- Heterozygous: the person has received a different allele for a particular trait from each parent; so if he or she has the condition and it is expressed, it is likely to be less severe.
- Homozygous: the person has received the same allele from each parent, and the disease tends to be more serious.
- OPMD: (see episode #47)
- Hypercholesterolemia: a genetic fragment is missing in a particular chromosome that prevents the LDL (the bad cholesterol) from being cleared in the plasma. This causes high cholesterol levels. The incidence of this disease in the western world is one in 500; in Québec, it’s one in 270. It’s as high as one in 150 in certain regions (regional founder effect) such as Kamouraska. The five epicenters for hypercholesterolemia are Kamouraska, Montreal/central Québec, Saquenay/Lac St-Jean, Gaspé and the north coast, and Beauce. The Maine Sun Journal (Lewiston-Auburn region) published an article in 2012 called The Franco Factor. It is behind a subscription firewall, but you can read a similar article in the Bangor Daily News called French Canadian genetic disorder can cause killer cholesterol levels in even the healthiest person.
- Early onset breast cancer: a significant number of women in Canada under the age of 50 are diagnosed with this disease. The founder immigrant came from Portugal.
- Clouston’s hidrotic ectodermal dysplasia: pocketed primarily in northern Vermont. It shows up as nail deformities, thickening of the palms and soles, and early-onset hair loss. It is mostly from Huntington County and comes from a late founder, only eight or nine generations ago.
- Charcot-Marie-Tooth disease: more prevalent in Québec. It’s a disorder of the peripheral nervous system; foot-drop is an early symptom. Thought to be the result of a founder mutation in four French-Canadian families. It can be dominant, recessive, or x-linked, and tends to be worse in males than in females.
- Type 1 Protein C deficiency: The founder couple are thought to have married in 1669 and settled on the Isle d’Orléans. They then made their way to Vermont. It is a blood-clotting disease found in France also.
These diseases are carried by the mother and passed on to all her children, but only daughters can pass it on.
- Leber hereditary optic neuropathy: symptom is loss of central vision when vision was previously normal. It is thought to be passed down by a fille du roi who married in the late 1660s and had five daughters. Centered in Montréal and the south shore of Québec.
25% chance of being expressed if carried by both parents
- Cystic fibrosis: found in Saguenay/Lac St-Jean region and Charlevoix. This region has 140 pages of male Tremblays in one church register. One in 15 carries this condition. It affects the digestive tract.
- Tay-sachs disease: found in Ashkenazi Jews, Acadians, and French-Canadians. They are three different mutations although the disease is the same. It affects the nerves of the spinal cord; it’s a rapidly moving condition.
Expressed in males because it’s carried by the female. If she passes on the diseased X-chromosome, there is no genetic material on the Y-chromosome to counteract it.
- Hemophilia: most well-known x-linked disease. Person bleeds for no particular reason because the blood does not clot.
- Colorblindness: most common x-linked disease. Red/green colorblindness affects men.
Other diseases that affect French-Canadians in larger numbers
- Multiple sclerosis: found in both males and females
- Restless leg syndrome: affects women more often than men
- Paget’s disease: causes deformities in the bones
- Familial Alzheimer’s disease: actively researched today
- Duchenne muscular dystrophy: worsens quickly; found most often in boys
BALSAC is a database begun by the University of Québec at Chicoutimi in 1972. Barbeau was one of the first in the 1960s to research the genealogy of people with these diseases. BALSAC continued this by at first constructing the genealogies of 37,000 people in the Saguenay/Lac St-Jean area.
Today BALSAC is also associated with McGill University, the University of Montreal, the University of Québec at Chicoutimi, and Laval University. The database now contains 3,000,000 names, including non-Catholics. They study the regions and the increase or decrease of frequency of a particular allele in a population, particularly when the group migrates.
BALSAC also uses the database for genetic epidemiology, or the study of the specific factors, including environmental, that determine the health and wellness of a particular area.
What can you do?
Determine family’s health history by exploring:
- family stories
- current symptoms showing up in the family
- death certificates
- military discharge records
- family interviews
- prenatal and newborn screening
- Couture P, Bovill E, Demers C, et al. Evidence of a Founder Effect for the Protein C Gene 3363 Inserted C Mutation in Thrombophilic Pedigrees of French Origin. Thromb Haemost 2001; 86:1000-6.
- Ghadirian P, Robidoux A, Shang P et al. The Contribution of founder mutations to early onset breast cancer in French Canadian Woman. Clinical Genetics Nov. 2009 Vol 76, Issue 5, 421-426.
- Kibar Z, Dube MP, Powell J et al. Clouston hidrotic ectodermal dysplasia (HED): genetic homogeneity, presence of a founder effect in the French Canadian Population and fine genetic mapping. European Journal of Human Genetics (2000) 8, 372-380.
- Laberge AM, Jomphe M, Houde L, Vezina H et al. A “Fille du Roy” Introduced the T14484C Leber Hereditary Optic Neuropathy Mutation in French Canadians. Am. J. Hum. Genet. 2005, 77:313-317.
- Simard LR, Viel J, Lambert M et al.. The Δ> 15 Kb deletion French Canadian founder mutation in familial hypercholesterolemia: rapid polymerase chain reaction-based diagnostic assay and prevalence in Quebec. Clin Genet 2004: 65: 202-208.
Summaries of many disorders can also be found in the articles listed in the bibliography for the first session.
OMIM, National Institutes of Health’s Genetic Website is a thorough resource focused on genetic research.
Articles may also be found on local library sites such as Academic Search Premier or obtained through inter-library loan.
Here are some articles you might find interesting:
- Canadian Cardiovascular Society Position Statement on Familial Hypercholesterolemia
- Former John Jay student fights for cure
- Whole-Exome Sequencing Reveals a Rapid Change in the Frequency of Rare Functional Variants in a Founding Population of Humans
- Dangerous disease linked to French-Canadian ancestry
- French-Canadian Ancestry and Relevant Health Conditions
- Genetic disease is ravaging Lancaster County’s Amish, and helping to change medicine for all of us: another group feeling the effects of an isolated founder population
- BALSAC Population Database
- Genealogy and “The French Canadian Disease”: OPMD
- L'”effet fondateur” québécois au service de la génétique
- French-Canadian disease prompts U.S. warning
- The “Jumping Frenchmen of Maine” Offer Lessons in Medical History, Human Behavior
UPDATE Sep 2016: Blogger Elizabeth Banas used information from episodes 47 and 48 in her post A Rare Neurological Disorder: Is There A Canadian Connection? Be sure to read her moving story.
Survey 47 results:
How long have you been researching your French-Canadian lines? Maple Stars and Stripes listeners reported in at:
- Less than a year-9%
- 1-5 years-14%
- 5-10 years-20%
- 10-20 years-20%
- More than 20 years-38%
This episode’s question is: Do you know anyone who has or that you suspect has a French-Canadian genetic disease?
The choices are: Yes; No; I suspect, but I’m not sure.
Participate in Survey 48 here.
There are only about two weeks left for you to enter our book give-away for a copy of Hélène’s World: Hélène Desportes of Seventeenth-Century Quebec by Susan McNelley, the book we featured in episodes 20, 33, and 43. If you’d like a copy of your own, here’s what you need to do.
If you have not signed up for the MapleStarsandStripes newsletter yet, just go to maplestarsandstripes.com/newsletter, sign up, and you’ll be automatically entered. If you already receive the newsletter, send an email instead to maplestarsandstripes [at] gmail [dot] com with “book contest” in the subject line. That’s it.
The deadline is midnight on May 31st. On June first, I’ll select a winner, email you, and get your mailing address. Good luck to all!
The American-French Genealogical Society
May 21, 9 AM: Bill Pommenville will present Doing Research From Home using Internet Research Tools. Classes are held at the AFGS Library, 78 Earle Street, Woonsocket, RI, and begin at 9:00 AM (unless otherwise noted).
The Franco-American Centre, Manchester, NH
Another French adventure is scheduled for Saturday, June 4. Details were not finalized at the time of this writing, so be sure to check out their website for additional details.
The Quebec Family History Society
- Sunday, May 22, 10 AM to 3 PM: a tour of Montreal’s Mount Royal and Notre-Dame-des-Neiges Cemeteries.
- Saturday, May 28, 1 to 3 PM, Johanne Gervais will present a seminar on How To Use MyHeritage Family Tree Builder.
Classes are held at the QFHS Heritage Centre and Library in Pointe-Claire, Quebec.
Lynda.com: Check out their course offerings, then try out a 10-day free trial by clicking the banner below.
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