3 : Parent And Child
The controversial technique, which allows parents with rare genetic mutations to have healthy babies, has only been legally approved in the UK. But the birth of the child, whose Jordanian parents were treated by a US-based team in Mexico, should fast-forward progress around the world, say embryologists.
3 : Parent and Child
Around a quarter of her mitochondria have the disease-causing mutation. While she is healthy, Leigh syndrome was responsible for the deaths of her first two children. The couple sought out the help of John Zhang and his team at the New Hope Fertility Center in New York City.
The paper reports new details about the procedure, such as the method used to transfer the mitochondria: freezing and heating the embryo before using an electrical pulse to fuse the mother's nucleus into the donor egg. The study also reveals that some diseased DNA from the mother was carried over inadvertently into the donor egg, which could have long-term repercussions for the child's health.
Scientists don't know what amount of diseased mitochondria would cause noticeable symptoms, or even disease, in a child created using genetic material from two women. But studies in mice have shown that mixtures of mitochondria can result in neurological disorders or metabolic conditions2.
A three-page editorial3 accompanying the study notes that the researchers had the baby's parents sign a consent form acknowledging that their egg was undergoing an experimental technique. But the form only described the procedure superficially, and did not inform the couple of the potential risks of using this method to create a child.
In addition to the production of reactive oxygen species due to the release of free electrons generated from the respiratory chain, mitochondria have few repair systems and therefore are subject to genetic mutations, causing diseases that affect approximately 1 in 5,000 people (Laureano, 2015). Mitochondrial diseases can affect organs that depend on energy metabolism, such as skeletal muscle, cardiac, central nervous system, endocrine, retina and liver (Nogueira et al., 2015; Laureano, 2015), giving rise to several incurable diseases, such as: deafness, diabetes mellitus, myopathies, glaucoma and others (Costa et al., 2016). These metabolic disorders, lead to inefficient oxidative phosphorylation, impairing cell energy production (Craven et al., 2017). They are difficult to diagnose and most of the time untreated, affecting adults and children (Nogueira et al., 2015).
Mitochondrial donation techniques give women with mitochondrial defects a chance to have normal children (Greenfield et al., 2017). The proposed technique was approved in 2015 in the United Kingdom, with the first individual being born in Mexico. However, mismatches between mitochondrial and nuclear genomes during this process may occur (Eyre-Walker, 2017). The technique also faces theological and ethical dilemmas concerning the involvement of the donor with the generated embryo (Bianco & Montagna, 2016), since the child born will have three distinct genetic materials, one will come from the father through the spermatozoa, another from the biological mother, represented by nuclear DNA and the third by the donor of the cytoplasm containing mitochondrial DNA without pathological inheritance, generating a "three-parent baby".
Cases such as this show that there are still uncertainties about the level of acceptable mtDNA heteroplasmy in the selection of embryos through PGD for the generation of healthy children. A phenomenon that contributes to the difficulty of identifying a safe percentage is the bottleneck effect (Mitalipov et al., 2014). The bottleneck is a hypothesis suggested from observations on changes in mtDNA heteroplasmy between generations and occurs in the ovary during oocyte development, possibly due to a marked reduction in the number of mtDNA copies in primordial germ cells, followed by segregation of mtDNA in mature oocytes (Wolf et al., 2017).
When the first baby born using a controversial procedure that meant he had three genetic parents was born back in 2016, it made headlines. The baby boy inherited most of his DNA from his mother and father, but he also had a tiny amount from a third person.
Others first create a fertilized egg, called a zygote. Then they collect the DNA-containing nucleus of this zygote, which can be transferred to another fertilized egg that has had its own nucleus removed. The resulting zygote also has three genetic parents.
Professor of Mitochondrial Genetics, Joanna Poulton gives her views on the recent announcement that a baby boy, the first child to be born using a new technique that incorporates DNA from three people, is now five months old.
This means the baby has three genetic parents: the father who supplied the sperm, the mother who supplied both womb and the egg nucleus, and an anonymous donor who supplied healthy mitochondria. Of these, the mitochondrial DNA is by far the smallest contribution. This type of three-parent baby is new, although other types have existed for many years.
"I knew that that tiny little bit of DNA is not responsible for such crucial stuff as your eyes color, your hair, your character and all [the] other important stuff," she says of the donor's DNA. It seemed, she says, "not very important for [the] child's appearance and his character, his mentality."
"This is the first time a human being is being created this way," says Jeffrey Kahn, director of the Johns Hopkins Berman Institute of Bioethics. Kahn chaired a U.S. National Academy of Sciences panel that examined the science and ethical issues raised by the three-parent procedure.
Kahn's panel concluded it could be ethical to try the procedure to try to prevent mitochondrial disease. But it is prohibited in the United States. So a doctor from a New York clinic traveled to Mexico to help a Jordanian couple conceive a child this way.
"There are fears that we are moving down the slippery slope towards designer babies," says Naomi Cahn, a professor of law at the George Washington University School of Law, referring to parents picking and choosing the traits of their children.
Now I need to emit event from parent to child component. I see in vue version 3 $on, $off and $once instance methods are removed. Application instances no longer implement the event emitter interface.
You would not listen from the child component for parent events, you would instead pass a prop down to the child and if the child component needs to update the data you would emit an event from child to parent to update the state.
If you were like me calling some event on this.$root.$on(...) and this.$root.$emit(...) in Vue2 from any parent/child to any child/parent for somehow keep your code cleaner rather then using bunch of emits and props respectively and have your code blows up..
To understand the idea of three-parent babies, we have to talk about DNA. Most people are familiar with the double helix-style DNA which make up the 23 pairs of chromosomes that are found in the nucleus of every cell in our body. It provides the instructions for building an entire organism and the proteins that drive our existence from conception until death. However, the DNA in the nucleus is not the only kind of DNA required for us to exist. There is also DNA tucked away in little compartments called mitochondria, that are found inside all of the cells in your body.
Just like nuclear DNA, mtDNA can have mutations that can lead to very serious, debilitating diseases, and in some cases, infertility for a woman carrying the defective mitochondria. Enter the third parent.
Parents with young children themselves make clear they are anxious about the effects of screen time. Fully 71% of parents of a child under the age of 12 say they are at least somewhat concerned their child might ever spend too much time in front of screens, including 31% who are very concerned about this.1 And some parents with a child in this age range already believe their child spends too much time on certain devices, including a smartphone. (It is important to note that this survey was fielded before the COVID-19 outbreak in the U.S. that closed many schools and led to widespread shutdowns and stay-at-home orders throughout the country.)
While a majority of parents with a young child say they are very (39%) or somewhat confident (45%) in knowing the appropriate amount of screen time for their child, they are also seeking out advice from others. Some 61% of parents of a child age 11 or younger say they have received advice or information about screen time from a doctor or other medical professional and 55% say the same about other parents, while 45% of parents of a child age 5 to 11 have turned to teachers for help.
Parents of a child age 11 or younger is used to refer to parents who report having a child age 11 or younger. In cases where families have more than one child in this age range, these questions asked the parents focus on one of those children, either their oldest or youngest child in this age range (based on random assignment).
YouTube has emerged as a key platform for both younger and older kids. Fully 89% of parents of a child age 5 to 11 say their child watches videos on YouTube, as do 81% of those who have a child age 3 to 4 and 57% of those who have child age 2 or younger. And while majorities of parents whose child uses YouTube credit the platform for entertaining and educating their children, a majority of these parents are concerned about their child being exposed to inappropriate content on the video sharing site.
But the conversation around screen time is not limited to children. Parents themselves grapple with their own device distractions. When asked if they spend too much, too little or not enough time on their phone, more than half of parents overall (56%) say they spend too much time on their smartphone, while about seven-in-ten (68%) say they are at least sometimes distracted by their phone when spending time with their children. 041b061a72