Doctor insights on:
Is Down Syndrome Caused By A Mutation
In genetics, a mutation is a change in the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element. Mutations result from unrepaired damage to dna or to RNA genomes (typically caused by radiation or chemical mutagens), from errors in the process of replication, or from the insertion or deletion of segments of dna ...Read more
Not mutation,number : Down syndrome is an abnormality of chromosome numbers, not a trait or mutation in the gene code. During conception only one of chromosome of each pair is given by both parents to the fertile egg.If a parent adds their 2 nbr 21chm to the other parents nbr 21, 3 end up in the egg ; the excess 21 causes the all the problems.Rare forms are causes by a extra piece of a 21, but that's another issue. ...Read moreSee 1 more doctor answer
Is there a type of mosaic Down syndrome that doesn't require the mutation to come from either parent to have a downs child?
Yes: A mosaic down syndrome child can come from a normal egg and normal sperm, produced by normal parents. The fertilized egg would start out normal with 46 chromosomes. It can divide into 2 normal cells, which themselves divide again. If on one of the early divisions, one cell ends up with an extra #21 chromosome and survives to continue dividing, the child will be mosaic with some trisomy 21 cells. ...Read moreSee 1 more doctor answer
Separate study: If you are having the one study done it is simple enough to arrange for the other study at the same time. They are separate tests and often done at a separate lab. ...Read more
Why do Down syndrome patient have their eyes slanted upward, is it caused by the chromosome 21, i need an explanation on why their face look different?
In the genes: All of our features are determined by our genes. The appearance of your eyes, nose, mouth, hair color, skin color, among other features are all inherited. When there is a defect in the gene coding, changes can occur. Facial features can change with in utero exposure such as alcohol (fas syndrome). For downs, the extra 21 causes low ears, slanted eyes, simian crease as well as organ problems. ...Read more
Extra chromosome 21: A woman's chances of giving birth to a child with down syndrome increase with age because older eggs have a greater risk of improper chromosome division. By age 35, a woman's risk of conceiving a child with down syndrome is 1 in 400. By age 45, the risk is 1 in 35. However, most children with down syndrome are actually born to women under age 35 because younger women have far more babies. ...Read moreSee 1 more doctor answer
Several possible: The features of down syndrome are dependent on the addition of one extra segment of a 21 chromosome which is more likely as women age .You can get this several ways. The traditional DS (~95%) has 3 copies of a 21 chromosome. About 4% have the specific extra 21 piece stuck on a regular chromosome (trans-location).About 1% have a mosaic of some normal and some 21 trisomy in variable amounts. ...Read moreSee 2 more doctor answers
Down syndrome is the classic presentation clinically of the congenital malformation syndrome also known as Trisomy 21. Classic features may include simian creases, epicanthal folds, upslanting palpebral fissures, flat nasal bridge, hypertelorism, low set ears, endocardial cushion defects of the heart, atlanto-axial joint instability, blood ...Read more
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