MNI researchers have located a genetic bottleneck that determines the proportion of mutated mtDNA that mothers transmit to their offspring. This is important because there are many copies of mitochondria in cells and their distribution in tissues has a role in the severity and symptoms of the disease. Therefore knowing how mtDNA is transmitted is essential for the understanding and treatment of a range of maternally inherited diseases, and provides an opportunity for genetic counselling and treatment.
Eric Shoubridge, neuroscientist at the MNI and lead investigator in the study.
This bottleneck occurs during the development of eggs in affected females. Only a small set of the female's mtDNA is selected to replicate resulting in the individual producing eggs with a wide range of proportions of mutated mtDNA. These eggs give rise to offspring with proportions of mutated mtDNA that differ from each other and are different from the proportion of mutated mtDNA in the mother.
This explains why the occurrence and severity of a disease from mutated mtDNA can vary in offspring of an affected mother. The identification and location of the genetic bottleneck in our study strengthens our knowledge of the rules and processes of transmission and improves our capacity for genetic counselling. An important application of this study is in the prevention of the disease at the prenatal stage because therapies for sick patients are usually ineffective, and the diseases are often fatal.
The study locates the bottleneck as occurring during the process of egg maturation in early postnatal life of a female, supporting the knowledge that mature oocytes or egg cells contain the full set of copies of mtDNA. That's more than , proteins!
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Like chromosomes, genes also come in pairs. Each of your parents has two copies of each of their genes, and each parent passes along just one copy to make up the genes you have. Genes that are passed on to you determine many of your traits, such as your hair color and skin color. Maybe Emma's mother has one gene for brown hair and one for red hair, and she passed the red hair gene on to Emma. If her father has two genes for red hair, that could explain her red hair.
Emma ended up with two genes for red hair, one from each of her parents.
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You also can see genes at work if you think about all the many different breeds of dogs. They all have the genes that make them dogs instead of cats, fish, or people. But those same genes that make a dog a dog also make different dog traits. So some breeds are small and others are big.
Some have long fur and others have short fur. Dalmatians have genes for white fur and black spots, and toy poodles have genes that make them small with curly fur. You get the idea! Scientists are very busy studying genes.
They want to know which proteins each gene makes and what those proteins do. They also want to know what illnesses are caused by genes that don't work right. Genes that have been changed are called mutations. Researchers think that mutations may be partly to blame for lung problems, cancer, and many other illnesses. Other illnesses and health problems happen when there are missing genes or extra parts of genes or chromosomes. Some of these gene problems can be inherited from a parent.
For example, take the gene that helps the body make hemoglobin say: HEE-muh-glow-bin.
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Studies highlight early childhood as a critical period for brain development and for setting in place the structures that will shape future cognitive, social, emotional, and health outcomes. Limited parental resources, including child poverty and lack of health insurance, and its attendant stressors have the potential to shape the neurobiology of the developing child in powerful ways, which may lead directly to worse health later in life.
What Is a Gene? (for Kids) - KidsHealth
Let's take the case of low birth weight. A study I co-authored with Robert Schoeni finds that babies born too soon or small suffer significant detrimental effects. Low birth weight -- defined in medical convention as less than 5. Our study, the first to link birth weight with adult health and socioeconomic success using a full, representative sample of the U.
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The poor economic status of parents during pregnancy leads to worse birth outcomes. In turn, these negative birth outcomes have harmful effects on children's cognitive development, health, and educational attainment, and also on their health and economic status in adulthood.
These effects then get passed down to the subsequent generation when the children, who are now adults, have their own children. Not only does low income and lack of health insurance for parents increase the likelihood of poor birth outcomes, but the effects are cruelly compounded for their kids: The lack of health insurance intensifies the negative impact of low birth weight. Evidence like this is a report card that shows how the life chances of poor children are being undermined.
Even more importantly, it is a challenge to do better. Being born at-risk does not have to be a life sentence for our children. The policy implication is that better access to health insurance and better prenatal care for low-income women may have significant effects on economic mobility. Policy measures can, and should, be designed to reduce the importance of these mechanisms if we wish to promote equality of economic opportunity.
There is the old adage that hereditary risk factors load the gun, but environmental risk factors pull the trigger. This suggests that intervening early -- and in ways that are based on the research evidence -- has the best chance of improving a child's health and well-being far into adulthood. Reducing the incidence of low birth weight, for instance, is a far more cost-effective policy than relying only on high-tech neonatal care.
Low birth weight infants account for a large and disproportionate share of public-health expenditures: More than one-third of the dollars spent in the U. We know, for example, that smoking during pregnancy doubles the risk of a low-weight birth. We also know at least one public policy can modify that risk: higher cigarette taxes, which have been proven to curb smoking among pregnant mothers, among others -- and to correlate to an almost immediate drop in the risk of low birth weight.
Yet because only a minority of pregnant women smoke and the vast majority of low-weight births are to nonsmokers, even large cigarette-tax hikes have only a modest impact on aggregate infant health. A more sweeping public-policy lever, of course, involves efforts to expand and promote the best possible prenatal care for the widest possible group of mothers.