How to Know if You’re at High Risk for Common Genetic Disorders
The common genetic disorder of mitochondrial DNA (mtDNA) may be more common in people of African descent than in Caucasians.
The finding, published this week in the journal Nature Genetics, may help to better understand why some African-Americans have more than one mutation on their mtDNA, or copy number.
A study published in the same journal suggests that a person with one mutation may have a higher risk of having a rare genetic condition known as mitochondrial arteriosclerosis, which is a condition characterized by the buildup of a plaques that is similar to Alzheimer’s disease.
The findings also raise the possibility that people of other ethnicities, such as Asian and Middle Easterners, may also have a lower risk of this rare condition.
The study, which involved researchers from Columbia University, found that African-American men had more mtDNA mutations than white men, while Asian-American women had more mitochondrial variants than white women.
“African-American males have more mtDNAs that have a high probability of having an mtDNA mutation than do Asian-Americans,” lead study author Dr. Richard G. Knecht, associate professor of medicine and biostatistics at Columbia University’s Mailman School of Public Health, told MTV News.
“The risk of mtDNA damage may be associated with ethnicity, but the cause remains unknown.”
Dr. Klecht and his colleagues looked at mtDNA variants associated with an autosomal dominant (ASD) variant in the mtDNA of 1,500 people.
The ASD variant is one of the genes that encode the protein that causes the mitochondrial arterio-artery disease (MAOA) disease, which affects 1 in 3,000 Americans, the highest rate in the world.
The ASD variant has been linked to schizophrenia, attention deficit hyperactivity disorder, and autism.
“We think that there may be a higher incidence of this variant in African- Americans, because they have higher frequencies of the ASD variant,” Dr. G.K. Kjeldsen, the study’s lead author and a medical geneticist at Columbia, said in a statement.
Dr. Wojciech Jelinski, the director of the Department of Genetics at the University of Chicago, also noted that the ASD risk is higher in African Americans.
“They have a very high risk of the ASD allele,” Dr Jelinsky told MTV.
“It seems to be a fairly recent mutation, and it has a higher mutation rate.”
African- American women have the highest risk of an ASD variant compared to other ethnic groups, which makes sense, as mtDNA is a relatively new genetic material, Dr. Jelinksi said.
The researchers also found that, among African-Amerindians, there was a significant association with mitochondrial variants that are more common on the X chromosome, which carries genes for the eyes and the nervous system.
These genetic variants were found to be associated more strongly with individuals of African-African ancestry, and the risk increased as one progressed through the mtDNA range, the range that contains genes for eyes, the nervous and immune system, and brain cells.
Dr Knebt says that, based on the findings, “we might not be looking at a causal relationship, but it is possible that there are multiple factors that may explain this.”
While the researchers found a genetic link between an ASD mutation and mitochondrial variants, the researchers cautioned that more research is needed to find out why the mutations occur.
“More research is required to confirm these results,” Dr Kjodlin said.
“At this point, the causal relationship between mitochondrial mutations and ASD is not clear, but at this stage, it is worth investigating.”
The research was supported by the National Institutes of Health.
Dr G.J. Kjellstrand, who co-authored the study with Dr Klech, is currently pursuing his PhD at Columbia.
For more news on mitochondrial DNA, visit MTV News’ website.