How Rare Genetic Diseases Arise in Some Populations Some disorders are much more common in certain ethnic groups or geographical regions. This phenomenon arises from what is known as the “founder effect” where a genetic mutation first appears in a single individual and is subsequently passed down to additional members of an isolated population over the course of many generations. Historically this has occurred in geographically remote areas, for instance in parts of Finland that may have been difficult to access because of mountains and fjords, and within groups that prefer to marry or find partners within their own community.Calling all Finns! Several genetic disorders are much more common in the Finnish population, including Salla disease, named after the region in Finland where it was first described, GRACILE syndrome, a devastating condition that results in very early death and affects about one in 47,000 people of Finnish descent, and neuronal ceroid lipofuscinosis, a group of nervous system disorders. We have also added a report on familial hyperinsulinism that contains mutations more commonly found in people of Finnish ancestry. Attention French Canadians! Several other genetic disorders are much more common in French Canadians who trace their ancestry to northeastern Quebec. These include ARSACS, a neurodegenerative disorder characterized by lack of muscle coordination, and ACCPN, a developmental disorder also known as Andermann syndrome. More Reports for Ashkenazi Jewish Ancestry Numerous disorders are much more common in people of Ashkenazi Jewish ancestry, including dihydrolipoamide dehydrogenase deficiency, which affects about one in 25,000 individuals and results from mutations that make it hard to metabolize certain amino acids and energy-containing molecules. We have also added a report for familial hyperinsulinism, a condition characterized by elevated insulin and low blood sugar levels. Although familial hyperinsulinism can affect people of different ethnicities, our report contains mutations that are more commonly found in people with Ashkenazi Jewish ancestry. Pay Attention to Peroxisomes Peroxisomal disorders arise from mutations that affect peroxisomes, small structures inside of cells that process lipids and toxins. Two of such disorders, Zellweger Syndrome Spectrum and D-Bifunctional Protein Deficiency, are very devastating – infants may suffer from seizures and typically do not survive beyond the first few years of life. More details on these and other conditions can be found on our website. People who are not 23andMe members can set up a free trial account to browse these and other reports.
health reports. Many of these reports fall into the “disease risk” category and cover complex conditions like Alzheimer’s disease, coronary heart disease, and hay fever (allergic rhinitis), to name a few. We also added new “trait” reports, for instance on the genetics underlying iris patterns, and new “drug response” reports, including one about metformin, a drug that helps the body respond to insulin and control blood sugar levels. We also added 20 new “carrier status” reports, bringing our total count up to 40+. Most of these reports cover rare recessive Mendelian disorders, which are single-gene conditions that are inherited by receiving one bad copy of a gene from mom and another bad copy of the gene from dad. With these reports, you can find out if you carry a mutation that you could pass on to your children. This information may be particularly important for prospective parents hoping to have a family. If you discover that your children could inherit one of these conditions, you can talk to a doctor or healthcare professional about what you can do. Read more about some of our new Carrier Status reports… Heart Working too Hard Familial hypertrophic cardiomyopathy is characterized by thickening of the heart muscle and is a cause of heart failure. The mutation in this report (MYBPC3 25bp-deletion) has only been described in people of South Asian ancestry and is inherited in a dominant manner, meaning that you only one need one bad copy of the gene to be at much higher risk for this disorder. Nearly 5% of people of South Asian descent are carriers of the mutation described in this report. Mutations associated with hypertrophic cardiomyopathy in other ethnicities are not covered in this report. Eating for Your Life People with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency are unable to convert some forms of fat into energy. As a result, they have a hard time maintaining blood sugar levels and must eat regularly to avoid acute episodes of lethargy, seizures and coma. About one in 15,000 babies is born with MCAD deficiency in the United States, but it is more common in Northwestern Europe. Hard of Hearing Pendred syndrome is a hearing disorder that affects newborns and young children. Some people with this syndrome also have thyroid abnormalities. Although the exact prevalence of this condition is not known, it is thought to account for up to 10% of all hereditary hearing loss.