The Lithuanian Genetic Code: What Makes Us Unique?

Have you ever wondered how the genes passed down by our ancestors are reflected in the DNA sequence of modern Lithuanians or what secrets the science of genetics can unveil about Lithuanian origins? These are precisely the questions that researchers at Vilnius University (VU) are exploring. They were the first to sequence the entire genome of a Lithuanian individual and are now seeking to ascertain insights into our origins and genetic connections with other nations and even analyse how genes determine our adaptation to environmental conditions.

What defines Lithuanians genetically? According to Dr Alina Urnikytė, Senior Researcher and Associate Professor at the VU Faculty of Medicine, Lithuanians are generally characterised by fair hair, light-coloured eyes, and an efficient metabolism for digesting fats. In this article, she explains the process of genetic research and its potential applications in medicine and reveals the reasons why the Lithuanian genome is so unique.

The human genome takes up about 50 GB of computer storage

Over the past few decades, significant advancements in DNA analysis technology have enabled scientists to sequence an entire human genome. However, this process remains complex and requires interdisciplinary knowledge. For instance, for genome sequencing, DNA must first be prepared for analysis, and only then can researchers perform the sequencing process.

“DNA is found in cells that have a nucleus. There are white cells in the blood – leukocytes that contain nuclei, which is exactly what we need. So, we take a blood sample from a person and extract the DNA. Then, we begin the sequencing process and read the DNA letters, scientifically called nucleotides. There are four types of nucleotides represented by four different letters. The entire sequenced DNA can be imagined as an extensive text composed of four recurring letters: A, T, G, and C. All of them reflect different nucleotides,” said Dr Urnikytė.

The Lithuanian genome is analysed using blood samples from individuals whose parents and grandparents have Lithuanian roots. This approach allows scientists to identify the genes and traits specific to the Lithuanian population. For geneticists to determine changes in the genome, at least two or three generations of the analysed population must have changed.

According to Dr Urnikytė, just sequencing a genome once is insufficient: “Currently, we use various technologies to sequence either the entire genome or only some specific positions. When we sequence the full genome, it consists of approximately 3.1 billion nucleotides. To ensure quality and accuracy, sequencing is repeated at least 35 times.”

A fully sequenced genome requires approximately 50 GB of computer storage. If only specific genome positions are analysed, a minimum of 700,000 nucleotide positions are examined, though ideally, it requires 1.8 million positions. The sequencing process takes three days, utilising technological equipment that processes the prepared DNA samples. Then, the devices generate preliminary sequencing data. Later, this data is uploaded to a supercomputer for analysis, which is why the whole process demands that we bring together expertise in both genetics and programming.

The Lithuanian genome: ancient, unique, and adapted

According to the researcher, defining a nation solely by its genome is challenging, as the genetic similarity between any two individuals in the world reaches 99%. However, she emphasises that the remaining 1% is rather significant: “As I’ve mentioned, the human genome consists of 3.1 billion nucleotides, so even a 1% difference accounts for substantial genetic variation, which determines the differences in our appearance and other traits. While the genome itself does not define a nation, we can analyse genes affected by natural selection that are associated with visible characteristics.”

Dr Urnikytė reveals that the Lithuanian genome is both ancient and unique, reflecting a complex historical background. Lithuanians carry a significant genetic heritage from Western hunter-gatherers, Indo-Europeans, and Late Neolithic Bronze Age Europeans, who supplemented our gene pool in later periods. This highlights the complex history of the Lithuanian population when different ancestral groups intermingled over time. Despite facing numerous historical adversities and deadly diseases, Lithuanians have preserved the uniqueness of their genome over centuries.

VU scientists have found that Lithuanians have genes that are influenced by natural selection and determine their fair skin, hair, and eyes. Hair colour varies in shades due to genetic diversity within the population. Similarly, Lithuanians’ eye colour often ranges from greyish to blue.

The geneticist also explains that genes determine not only the fair complexion, hair, and eyes of Lithuanians but also other physiological traits: “Some genes, shaped by ancient rather than modern natural selection, were influenced by local pathogens and are linked to more efficient fat metabolism. However, we have not yet been able to identify their exact function. My hypothesis is that these genes were inherited from hunter-gatherer ancestors who needed them not only to break down fats, as they consumed a lot of fish and meat but also to maintain energy levels in a cold climate. Since this is just a guess, we plan to continue researching these genes.”

Why are Lithuanians fair-haired and blue-eyed?

Like other populations, Lithuanians possess certain genes that can affect their health and adaptation to environmental conditions. Genes that develop over long periods of time often reflect geographic factors, diet, climate conditions, and other historical influences.

“When favourable living conditions emerged in Lithuania after the Ice Age, the early settlers had to adapt to the environment over time to survive in a climate with limited sunlight. The hunter-gatherers who migrated to this area initially had darker skin and hair, along with blue eyes. Later, their skin lightened to enhance vitamin D absorption, which is crucial for human health. Vitamin D is essential for maintaining strong bones, particularly for women, as it plays a vital role in pelvic bone structure,” explained Dr Urnikytė while summarising the reasons for the appearance of Lithuanians.

According to the researcher, if vitamin D is not absorbed sufficiently, the pelvic bones can soften, making childbirth more difficult for women and posing a potential threat to population survival: “The primary goal of humans is to survive. As a result, they adapted, and fair skin, hair, and eyes became dominant traits in the region.”

The Associate Professor notes that the Indo-Europeans, who arrived in the Lithuanian territories later than the hunter-gatherers, introduced agriculture and animal husbandry to these lands. Thus, at that time, the inhabitants of the Lithuanian territory began consuming milk, which, according to Dr Urnikytė, is why some Lithuanians today can tolerate lactose: “Humans, naturally, are unable to digest lactose – the sugar found in milk. One example of natural selection, a genetic mutation allowing lactase production, occurred relatively quickly, within just a few thousand years (which is rapid in evolutionary terms), so people adapted. Yet, even today, not everyone carries this mutation, which is why some people remain lactose intolerant.”

Latvians and Lithuanians are bound by genetics

According to the researcher, Lithuanians share the closest genetic ties with neighbouring populations, particularly Latvians. A few months ago, a new article was published, presenting the results on genetic connections between Lithuanians, Latvians, and Indians. It demonstrated a significant genetic similarity between the two Baltic nations. Hunter-gatherer populations dominated the present-day territories of Lithuania and Latvia until approximately 5000–4500 BCE, leaving a significant genetic imprint that remains visible in the modern gene pool of both nations.

“Interestingly, northern Samogitians (Žemaičiai) exhibit a unique genetic component that is also specific to Latvians, while those from the southern highlands of Aukštaitija – another ethnographic region of Lithuania (Aukštaičiai) – possess a genetic component characteristic of Slavic populations. The genetic component predominant in northern Samogitia likely traces back to the early Baltic ancestors, the Curonians, whereas in southern Aukštaitija, we observe genetic influences from the Sudovians (Yotvingians),” noted the researcher.

Is the genetic code the key to a healthier life?

Dr Urnikytė states that the genetic information of every person may hold valuable insights into disease susceptibility and individual responses to medication. In the future, Lithuanian genomic features can help identify genetic predisposition to certain conditions such as cardiovascular diseases, diabetes, or cancer. By identifying individuals at higher risk for certain diseases, we can take preventive steps: adjusting lifestyle, increasing the frequency of health check-ups, or starting early treatment with targeted medications.

“One of the fields that could benefit from Lithuanian genome research is pharmacogenomics, which explores the biochemical mechanisms of inherited responses to medications. Like other populations, Lithuanians may possess specific genes that influence their body’s reaction to certain drugs. This is key in determining optimal treatment methods, appropriate dosages, and choice of medicine. For example, certain genes can indicate which medications will be safe and effective and which could cause adverse reactions or unwanted side effects,” said Dr Urnikytė.

Lithuanian genome research may also pave the way for personalised nutrition, allowing dietary recommendations to be tailored to Lithuanians based on their genetic predispositions. “As for the genes that have already been identified – which have been shaped by natural selection and are linked to fat metabolism – we plan to cooperate with other scientists in life sciences and cardiology to investigate them further. Our goal is to uncover connections with cardiovascular diseases and determine which dietary components are most efficiently absorbed based on genetic characteristics,” concluded the researcher.