Can a Baby Have Chromosomes From Two Father's
by Marina Watanabe
figures by Elayne Fivenson
Hours afterwards giving birth, my sister sent a picture show of her newborn baby to our family group text. In what I can only assume was a painkiller-induced brume, she wrote, "The baby looks exactly like me!!!"
The baby did not wait exactly like her.
The baby, like all newborn babies, looked exactly like a white potato.
This idea of children beingness "mini mes" of their biological parents is a common conversation piece, and people oftentimes joke that the child is a clone of ane parent or the other. Despite these jokes, it's generally understood that it takes ii to brand a baby ( for the most part!! ) and that one-half the babe'southward Dna comes from an egg and half from a sperm. But sometimes, a real "mini me" is born with the majority of DNA coming from only one parent.
Family unit matters
In the Czechia , a deaf nine year old child underwent genetic testing to try to pinpoint the cause of the deafness. Apart from the length and width of the patient's legs slightly differing, there were no features to marker the kid as existence particularly out of the ordinary. The genetic testing results showed that the patient had two copies of a specific mutation, or alteration, in the genetic code. Interestingly, though, the mutation in question was not thought to crusade deafness.
To brainstorm unraveling the mystery of the human relationship betwixt the mutation and the patient'southward deafness, the doctors tracked the mutation within the family. Classical genetics states that since the patient had two mutant copies of the cistron, both parents must too have the mutation and they both must have passed it onto their child. The parents underwent genetic testing and it was determined in a baroque twist that only the father had the mutation. Before things could derail into a confusing and seemingly impossible game of "Who's the Mommy?!," the doctors did further genetic testing to reach a jarring decision: The patient's Deoxyribonucleic acid was nigh exclusively from the father. Also, I forgot to mention–the patient is a daughter.
How we inherit genetic material from our biological parents
DNA is the instruction transmission of what makes you who you are, and it is constitute in your trunk in the form of 23 pairs of chromosomes (for a total of 46 chromosomes). You got 1 ready of 23 chromosomes from one parent inside a sperm, and the other 23 from the other parent inside an egg. Because we accept 2 copies of our Deoxyribonucleic acid, humans are what's known every bit "diploid" and this is annotated as "2n." Almost all the cells in your torso incorporate a copy of this full set of 23 pairs of chromosomes yous got from your biological parents. The exception are gametes, which are sexual activity cells (sperm or eggs), that only contain 23 chromosomes—not 46. Since they only incorporate one copy of our genetic information, gametes are 1n instead of 2n.
Unremarkably, the cosmos of gametes in an adult male or female is very straightforward (Figure i). For each chromosome, y'all start with the full gear up consisting of ii copies—one from each parent. Through a process called meiosis , these two chromosomes duplicate themselves (so you lot end up with four copies of each chromosome) and ultimately split into four gametes containing simply ane of each chromosome–meaning each gamete contains only half the corporeality of Deoxyribonucleic acid required for a human. This "halving" process occurs simultaneously across all 46 chromosomes, leading to the product of many gametes containing 23 chromosomes each. Subsequently meiosis, a sperm and an egg are then gratuitous to combine their incomplete genetic cloth to create a genetically consummate jail cell known as a zygote. This single-celled zygote is what grows into a new human.
Redefining single parenting
In the instance of the ix twelvemonth old daughter, she did not receive the normal half and half ratio of DNA from her parents. Though the doctors were trying to diagnose the cause of her deafness, they instead diagnosed her with genome-wide uniparental disomy or diploidy (GWUPD). In this condition, a person will non inherit 23 chromosomes from ane parent each for a full of 46, but will instead inherit almost all chromosomes from one parent. In this way, one person is essentially both biological "female parent" and "father" to a child. This is an incredibly rare condition, and every bit of 2018, only approximately 21 cases have been reported .
A curious feature of GWUPD is the fact that all of the patients affected are girls and women who accept inherited mostly their begetter'south genetic material. The reason why the single genetic parent has thus far always been the male parent is not yet known due to the fact that the condition is and so rare and it is experimentally difficult to understand a process that is taking identify in the very early on zygote.
Though scientists however do not fully understand GWUPD or its causes, they do take a theory . They believe that, much similar in classical zygote formation (Figure 1), a sperm and egg met to form a zygote. At this betoken, both the Dna from the sperm and the Dna from the egg should accept begun replicating themselves so that the one-celled zygote could brainstorm making more and more than cells with both sets of Deoxyribonucleic acid in order to create a fully-functioning human embryo (Figure 2a). Withal in the case of GWUPD, for whatever reason, the genetic information from the female parent did not replicate properly, leading to 2 populations of cells–those with Dna from both parents and those with DNA only from the father (Effigy 2b).
In GWUPD patients, these different cells with dissimilar chromosomes go along to compose different parts of the body so that, depending on the tissue, the genetics may vary. For case, in the case of the nine year quondam Czech girl, the percent of cells containing simply her begetter's Deoxyribonucleic acid was 93% in her blood simply 74% in her saliva. So while she is mostly equanimous of her father'south genetic fabric, she does still have some of her mother in her.
Side effects may vary
GWUPD patients often have high levels of insulin, asymmetrical body parts, seizures, astringent developmental delays, are born prematurely, and/or are more susceptible to developing cancer. Since each patient derives their DNA from their private and unique parent, the genetics of the patients vary wildly from one to the other and their symptoms vary. One of the reasons why the case of the Czech girl was and so interesting to doctors was the fact that she did not nowadays with most of these common symptoms, merely instead exhibited only deafness and asymmetric legs. Although they followed her for three years (publishing the paper virtually her when she was eleven), her doctors were unable to determine the cause of her deafness.
Stranger than fiction
Nosotros sometimes presume that creating a human life is a simple and straightforward process. However, when nosotros meet patients with GWUPD, we understand just how easily the process of creating new life can go awry. The cosmos of a daughter from just a man's genetic data sounds like something from Science Fiction (and has actually been the basis for an episode of Doctor Who !), but it is a phenomenon that very much exists and tin accept very negative consequences. While we may joke that a child is their parent'south "mini-me," information technology is interesting to note that this is an bodily possibility in the world of biology. Having "likewise much" Dna from 1 parent might non seem similar a trouble in and of itself, only it is proof that genetic diversity is important for life.
Marina Watanabe is a PhD candidate in the Biological and Biomedical Sciences graduate program at Harvard Academy. She loves her murphy niece very much.
Elayne Fivenson is a third-year Ph.D. pupil in the Biological and Biomedical Sciences program at Harvard Medical School, where she is studying the genetics and biochemistry of the bacterial prison cell envelope
Cover paradigm: "Karyotype of a human male"
For More Information:
- Read about this interesting case of a patient with generally maternal DNA who has cells that are Twenty (biologically female person) or XY (biologically male) depending on where they are sampled from.
- Uniparental disomy is GWUPD on a pocket-size scale where only one chromosome pair or role of a chromosome pair comes from ane parent. This is very dissimilar from GWUPD where well-nigh all of the chromosomes come from i parent.
- Run into this Khan University page for an introduction to classical genetics and inheritance .
- This Khan Academy link covers meiosis and how information technology leads to genetic multifariousness. Lessons on this page explain a process called "recombination" that ensures genetic diversity in offspring. Recombination explains why siblings are genetically different from each other even though they share the same parental "source cloth" and why GWUPD patients cannot exist regarded every bit clones of their fathers.
Source: https://sitn.hms.harvard.edu/flash/2019/like-father-like-daughter-the-creation-of-children-with-parentally-biased-dna/
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