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Lecture 4 : Genetic Factors Overview

Lecture 4 : Genetic Factors Overview. GENETICS GENETIC FACTORS Gender Race Blood Type Other Genetic Factors FOETAL AND EARLY LIFE INFLUENCES. Genetics. The human body is composed of 75 trillion cells. Almost all of these cells contain a copy of your DNA.

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Lecture 4 : Genetic Factors Overview

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  1. Lecture 4 : Genetic FactorsOverview • GENETICS • GENETIC FACTORS • Gender • Race • Blood Type • Other Genetic Factors • FOETAL AND EARLY LIFE INFLUENCES

  2. Genetics • The human body is composed of 75 trillion cells. Almost all of these cells contain a copy of your DNA. • The DNA molecule looks a bit like a spiral staircase. Each step is made up of 2 of 4 bases (Adenine, Cytosine, Guanine, Thymine). A is always joined to T and C is always joined to G. • This pairing of bases enables DNA to be replicated exactly each time a cell divides. • Human DNA contains about 3 million base pairs. • Growth occurs through cell division.

  3. Protein Production • The DNA in the nucleus of each cell is divided into 46 chromosomes. • Specific sections in specific chromosomes form a gene. There are 20,000 to 30,000 genes. • The sequence of the nucleotides within each gene provides the formula for a protein, and thereby controls a particular trait. • Your genes are inherited from your parents.

  4. Gender • Gender: Females have higher morbidity rates, but lower mortality rates. They therefore have higher life expectancy. • Given that there are only two sexes, males and females are normally studied separately. • Gender differences in mortality are not necessarily genetically determined. Females have a lower life expectancy in some countries, especially Islamic countries, suggesting that life expectancies may also be influenced by gender roles.

  5. Race • Different racial groups appear to have different susceptibilities to certain diseases (e.g. skin cancer in fair skinned people, rickets in UK Asians). • It is difficult to separate the biological effects of race from the effects of social context – e.g. different racial groups in any given society tend to suffer different degrees of social deprivation. • Nevertheless, race should not be discounted as a possible contributory factor.

  6. Blood Type • Blood can be classified in several ways, but the ABO classification is the best known. • This has four categories: A, B, AB and O (depending upon the presence of the A and B antigens on the surface of the red blood cells). • The susceptibility to certain diseases appears to be influenced by blood type.

  7. Blood Type And Disease

  8. Geography Of Blood Types • Blood type is genetically inherited, and has a geography reflecting past migration patterns. • Blood types A and O dominate in the UK in Ireland. • Blood type A in the UK is more common in the areas colonised by Vikings, Angles, Saxons and Normans. Blood type O is more common in the Celtic fringe. • Blood type A in Ireland is more common in the east, type O in the west. • Blood type might account for some of the spatial variations in some diseases.

  9. Type A Type O

  10. Type A Type O (Source: Sean Cremin)

  11. Early Life Influences • The geographical pattern of degenerative diseases in adults has been observed in many studies to be similar to the pattern of infant mortality in the same cohort 60 years previously, suggesting that factors causing infant mortality might have a lasting impact upon the survivors. • Individual level studies show that the risk of adult disease is related to birthweight, suggesting that the risks of adult disease may be determined in the womb. • David Barker has conducted numerous empirical studies and developed a very plausible theory linking foetal development with adult diseases.

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