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Identical Twins Genetic Makeup
Not always: They would be no more likely to look alike than any other siblings. ...Read more
From a medical standpoint, "genetic" refers to the potential heritability of various medical conditions. While some conditions are inevitable (at some point in one's life) as a consequence of simple genetic heritability (eg huntington's disease), a large number of medical conditions (including all behaviorial health disorders) are the expressed final pathway of a ...Read more
If twins are monozygotic but dichorionic are they less completely identical genetically than monochorionic twins ?
The same.: Monozygotic dichorionic is another term for monochorionic diamniotic twins. They are expected to be genetically identical in both cases because they come from one original fertilized egg. ...Read more
Is down syndrome dominant , recessive , polygenic inheritance , multiple alleles , sex linked, codominance , or incomplete dominance ?
Yes: Fraternal twins are 3 times as frequent as identical. Fraternal twins happen when there is double ovulation and 2 eggs get fertilized. They are the type of twins that run in families. Identical twins come from 1 fertilized egg which separate in early gestation. Depending on when they separate, the babies can be in 2 distinct sac (di/di), 2 sacs within a shared sac (mono/di) or 1 sac (mono/mono). ...Read moreSee 1 more doctor answer
Some do some don't: If two twins share the same sac, they're identical. (almost always works.) the pathologist who examines the placenta can tell. Identical twins can have two sacs, or one sac; if there are two sacs, there can be one or two chorions. Fraternal twins won't share chorions or sacs. ...Read more
Good question. : The answer is no, a small number of patients with early onset breast cancer who carry a bad brca 1 or 2 mutation develop it "de novo", meaning that it started with them (after all, someone has to be the first to have it). Depending at which stage in development it happens, it may affect them to a different degree and may or may not be passed to their children. Some other cancer syndromes.. ...Read moreSee 1 more doctor answer
Both : A fertilized egg cell will split into two separate embryos, and grow into identical twins. A common misconception about identical twins is that the trait for having them is passed on to future generations through the mother's genes. But the truth is science doesn't know the reason why identical twins occur. At this time, we can just say that they're examples of a nine-month double miracle. ...Read more
Not necessarily.: Identical vs. Fraternal twins are archaic terms that no longer apply to the modern perinatal terminology., however are still generally true and understandable to lay people. The color of eyes is not the determining factor in zygocity or chorionicity of twins - check prenatal records and placental pathology! ...Read more
Yes: While the diagnosis may be suspected, it can only be confirmed by close examination of the placentas or genetic testing before/after delivery. Usually with early ultrasounds, we can be pretty sure about identical or monozygotic twins. It means that during very early embryo development, one embryo split into two. ...Read more
Probably not: Developmental delay/disabilities have many causes, most of which are not genetic. If you are known to carry a genetic disease associated with developmental disability, testing can usually be performed on each fetus individually while still in the uterus. If you are thought to have identical (monozygotic) twins or triplets, then they would all share identical genes. ...Read more
No: Identical twins share some disorders to a high degree (e.g., adhd, bipolar disorder), but learning disabilities are not a specific disorder, rather a heterogenous grouping of brain dysfunctions that may affect learning. Multiples are at higher risk for ld's because of shortened gestation, increased incidence of neonatal problems, & decreased intrauterine nutrition. ...Read moreSee 2 more doctor answers
Clarifying Q & A: In the general population, the incidence of a brca1 mutation is between 1:500 to 1:800. It is much lower for brca2. For a woman or offspring to inherit the gene from a parent who has one copy of the mutated gene, there is a 50% chance of acquiring the gene in question. It is autosomal dominant and therefore can manifest its deleterious consequences by itself without need of a second copy. ...Read more
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