Överkalix study

Location of Överkalix, Sweden

The Överkalix study was a study conducted on the physiological effects of various environmental factors on transgenerational epigenetic inheritance.

The Överkalix study is a groundbreaking investigation centered on understanding the physiological effects that various environmental factors have on transgenerational epigenetic inheritance.

Study Methodology

Conducted within the confines of Överkalix, an isolated municipality situated in northeast Sweden, researchers utilized extensive historical records, including data on harvests and prevailing food prices of the era. The study cohort comprised 303 probands, consisting of 164 men and 139 women born in the years 1890, 1905, or 1920. Further in-depth analysis was conducted on their lineage – a total of 1,818 parents and grandparents. Notably, 44 of these probands were still alive as of 1995 when the mortality data was last updated. The research also meticulously calculated Mortality risk ratios (RR) for offspring and successive generations, using the availability of food supply as a metric, corroborated with the historical records.

Key Findings: Participant Characteristics

Several intriguing patterns emerged from the study. Among them:

Male probands displayed a higher body mass index (BMI) at age 9 if their fathers began smoking at an earlier age. No similar correlation was observed in female probands. The food supply availability to paternal grandfathers impacted only the grandsons' mortality RR, whereas the maternal grandmother's food supply influenced just the granddaughters' mortality risk. Notably, an abundant food supply during the grandmother's youth correlated with a twofold increase in her granddaughter's mortality risk ratio (RR).

Delving into Transgenerational Inheritance

Central to the study's findings was the transgenerational epigenetic inheritance observed during the slow growth period (SGP). The SGP is a critical developmental phase preceding puberty, during which external environmental factors exert a pronounced influence on physiological development. In the context of the Överkalix study, the SGP was demarcated as ages 9-12 for boys and 8-10 for girls. The inheritance patterns were particularly prominent if the exposure occurred during the grandparents' SGP or the gestation phase of the grandmother. It was also noted that a deficient food supply for the father and an abundant supply for the mother were associated with a reduced risk of cardiovascular diseases in their offspring.

Gender Disparities

The study brought to light compelling gender-specific effects. Only the female probands manifested a twofold surge in mortality RR when their paternal grandmother had abundant food access during her SGP, as contrasted with those whose grandmothers faced food scarcity during the same period.

Unraveling Paternal Imprinting

These gender-specific trends can be attributed to a phenomenon known as parental imprinting. This intricate process leads to allele-specific variations in transcription, DNA methylation, and DNA replication timing. Imprinting is pivotal in human growth, and its aberration can culminate in specific diseases. This epigenetic mechanism is established during gametogenesis as homologous DNA traverses through the sperm or egg. As this process progresses from embryogenesis to adulthood, alleles of imprinted genes perpetuate in two distinct epigenetic forms: paternal and maternal. Consequently, these genomic imprints are hereditary and serve as indicators of the parental origins of specific genomic regions.

Genetic Imprinting: A Broader Perspective

While approximately 1-2% of human genes are believed to be influenced by parental imprinting, currently, this phenomenon has been recognized in fewer than 100 distinct genes.

See also

• Dutch famine of 1944

Överkalix study Resources
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