Smoking and Drinking Potentially Linked to Genetics

 

Drinking and smoking have been potentially found to be genetically linked in a recent study published in Nature. The researchers found more than 3,500 genetic variations that potentially affect smoking and drinking behaviors in a genome-wide association study. This study included almost 3.4 million people with African, American, East Asian, and European ancestry. Of the 3.4 million people, 21% had non-European ancestry.

The researchers identified 3,823 genetic variants that were associated with smoking or drinking behaviors in individuals. Of the more than 3,500 variants, thirty-nine were linked to the age at which individuals started smoking, 243 were linked to the number of cigarettes smoked per day, and 849 were linked to the number of alcoholic drinks consumed per week.

In my opinion, although these behaviors may be genetically linked, smoking and drinking are still environmentally influenced. The genetics part could be more so to do with how one reacts when they do smoke and drink. The genetic links could also affect how easily the risks of other health conditions arising from drinking and smoking, as smokers are more likely to develop heart disease, strokes, and lung cancer. Likewise, drinking can lead to the development of multiple chronic diseases, such as high blood pressure, heart disease, cancer, and multiple mental health issues and memory problems.

Genetic Variants Linked to Height

For decades, scientists have been in search of the common genetic factors influencing one's height and have had no luck. After studying almost 5.4 million people’s DNA, a team of geneticists have conducted the largest genome-wide association study of its kind, identifying over 12,000 height influencing genetic variants. Depending on the person’s ancestry, up to 40 percent of all variation in height can be explained by these variants typically clustering around the sections of genome associated with skeletal growth. This almost 20-year study has resulted in the discovery of the majority of genetic variation linked to height and the growing sample size can inform us about traits controlled by multiple genes.

     This monumental study can one day help physicians identify deficiencies and hidden diseases in individuals who are not meeting their predicted genetic height. The current outcome of the genome-wide association studies (GWAS) demonstrates its importance in the biological basis and heritability of diseases. Together, GWAS and 23andme were able to collect data from seven times more people than in original studies. The results revealed common single nucleotide polymorphisms (SNPs) associated with height. These SNPs make up 40 percent of variation in height of European descent and 10 – 20 percent for those not of European ancestry. This difference is likely due to the study composition being mostly European individuals, so there is a lack of diversity in the study. Increasing the non-European population in the study could prove the study to be more accurate in its findings of genome height influencing regions. Additionally, a more diverse cohort could help determine if specific groups are more likely to have certain genetic variants. With the knowledge collected, further research can be conducted to trace the effects of individual variants on height and could reveal correlations with other common conditions influenced by multiple genes.  

Genes that have Effect on Head and Brain Size

            It was recently discovered that the size of children heads is not only related to the size of their skull, but also to the size of their brain. This discovery was published in Nature Communications, on how a genome-wide analysis can identify the genetic effects of head size and if it is related to the size of the brain. Up until the age of six, children and baby heads are measured throughout their life to make sure they are having healthy growth developments with their brain as they age. However, scientists at the Max Planck Institute (MPI) researched a genome-wide study (GWAS) with 46,000 adult and children to collect data on the effects of head size and brain size. The team suggests from the data collected, that an adult’s final head size is genetically predicted at a young age. The team also discovered that a rare gene, that about only two percent of the population contains, is called TP53. TP53 is a gene that encodes for p53, which controls cell division. TP53 is known to have mutations, but p53 is known as a gene to thicken the membrane of the skull bone, which can result in a larger brain size. 

       Although this article is very interesting that scientists are researching genes that can determine how large a person’s brain can become just by measuring the size of a person’s head when they are a baby. I do not think that the scientists have enough information to be able to say they can measure a baby’s head and determine if that baby will grow up and be the smartest child in school or an average child in school. The scientists only discovered that the TP53 gene can encode to the p53 protein which may be a factor to the thickness of a person’s skull, but this gene is only found in about two percent of the population. There would need to be more studies on the TP53 gene to determine if it actually is the factor for a larger head size, which can then determine if a larger head size results in a larger brain.

The genes for your face

A team of scientists from the University of Pittsburgh in Pennsylvania has further advanced the understanding of how gene variation can contribute to the diversity of facial shapes and sizes. Their genome-wide association study, published in PLOS Genetics, analyzed the association between 20 facial characteristics measured from 3D images of 3,000+ healthy individuals and about one million single base pair variations called SNP's. They succeeded in identifying genetic variants that contribute to the facial morphology of a normal human. Their analysis of the study concluded that certain facial features had statistically significant associations with certain SNP's. Various traits that compose a person's face, such as nose size, facial width, the distance between the eyes, and the distance between the lips and eyes, originate from specific genetic variations. Variation in specific regions of the genome relates to the kinds of distinguishing facial characteristics that give us our unique identities, and it also explains why we share facial features in common with our close relatives than with unrelated individuals.  This insight to understanding how facial shape/size is controlled by one's genes can also be useful for understanding craniofacial development and abnormalities.

Dr. Seth Weinberg, corresponding author of the study, says: "What is exciting is that many of these associations involve chromosomal regions harboring genes with known craniofacial function. Such findings can provide insights into the role genes play in the formation of the face and improve our understanding of the causal factors leading to certain craniofacial birth defects."

I think this article is awesome because it marks the beginning of the genetic understanding of human facial morphology.  Perhaps this knowledge will eventually allow us to create forensic facial reconstructions of a person from the DNA left of them. The ability to connect specific genetic variants to ubiquitous facial traits can also inform our understanding of normal and abnormal craniofacial development.  Their study was limited to a population of individuals with European ancestry, but it'd be interesting to analyze the genetic developmental relatedness of other worldly populations, e.g. individuals with Down Syndrome.

Neurodermatitis Genes Influence Other Allergies

There is a link between the skin condition atopic dermatitis and asthma, and it is tied to specific genetic loci that present a risk. The Max Delbruck Center for Molecular Medicine in the Helmholtz Association, where research was conducted on this disease, found seven genetic risk loci important to both diseases. The data used was collected from over 20,000 people. Atopic dermatitis has existing regions that determine the risk for the disease, which happen to also be the same regions that follow a typical allergic path that leads to asthma. The usual pattern, in which atopic dermatitis forms early in life, followed by food allergies and then asthma, is referred to as the atopic march.

In order to come to a basis for discovering the connected regions, the researchers performed a meta-analysis specific to genome-wide association studies, in which both patients and healthy individuals were compared. Within these bounds, the cases focused on individuals who developed atopic dermatitis and then asthma. The studies were concerned with Single Nucleotide Polymorphisms. Two regions in particular were most of interest, as they demonstrated the greatest connection between atopic dermatitis and asthma. It was not of great surprise that there are connections between allergic diseases, as the same genetic loci that produce certain factors should be able to cause other similar variations. If there are specific genetic loci that are associated with allergic conditions, it would make logical sense that many different expressions could result from the same area.

Being that this was one of the first research studies conducted on atopic dermatitis with a focus on genetic possibilities, it would be interesting if similar research was conducted on other related allergic diseases.