- Andermann syndrome, or agenesis of the corpus callosum with peripheral neuropathy (ACCPN)
- Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS, also called SACS) is a rare neurodegenerative disease that begins in childhood. About 1 in 22 French-Canadians from the Charlevoix and Saguenay-Lac-St-Jean regions of northeastern Quebec carries a mutation that causes the disease, which affects 1 in 2,000 people in this group. It can also occur among other populations. [PMID 8472930] [PMID 21450511] [PMID 16736723] [PMID 21726565]
- Cystic fibrosis appears in about 1 in 1,000 infants in one isolated region of Quebec.  [PMID 9618063]
- Familial hypercholesterolemia is an autosomal dominant condition caused by mutations in the LDL cholesterol receptor gene.
- Hypertension is associated with the T allele of SNP rs5370, but only in individuals who are not physically fit. [PMID 17938376]
- Leigh syndrome, French-Canadian type (LSFC), is caused by a mutation carried by 1 in 28 people in one region of Quebec. OMIM [PMID 12529507]
- Lipoprotein lipase deficiency is 100 times more common in parts of Quebec than elsewhere.
- Mednik syndrome, a severe inherited disease caused by defects in the adaptor protein gene AP1s1, was identified in 2008.   
- Oculopharyngeal muscular dystrophy (OMD) is an autosomal dominant disorder that appears in the fifth or sixth decade of life.
- Tay-Sachs disease [PMID 17259242] occurs at a higher rate among Ashkenazi Jews and people of Cajun and French-Canadian ancestry.