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Punnett Square Down Syndrome
Chromosome defect: Ds is one of the more common chromosome (c) defects that can survive pregnancy (many others miscarry).Eggs are supposed to have a single 21c & combine with the 21 from dads normal sperm.Here a pair of moms 21c +dad's 21 creates a baby with the extra 21c in all tissues. This extra material confuses the creation of body parts causing ds. Various prenatal tests can pick up signs early on.
DNA defects: Chromosome 21 seems to be the cause. Two most common types are trisomy 21 where ther is an entire extra chromosome in each cell. The other is translocation where only an extra piece of the chromosome is found. It can be an isolated defect or an inherited defect. Rare exotic forms include polyploidy and haploid forms and chimeras. Sorry you asked?See 1 more doctor answer
Chromosome defect: Ds is one of the more common chromosome (c) defects that can survive pregnancy (many others miscarry).Eggs are supposed to have a single 21c & combine with the 21 from dads normal sperm.In ds the pair of moms 21c +dad's 21 creates a baby with the three 21c in all tissues. This extra material confuses the creation of body parts causing ds. Various prenatal tests can pick up signs early on.See 1 more doctor answer
Down syndrome: Down's syndrome may be detected before birth (prenatally) or after birth (postnatally). It cannot be cured but treatment and support can help someone with Down's syndrome to lead an active life. A number of advice and support groups are available for people with Down's syndrome and their families and carers.See 1 more doctor answer
Mistake in chromosom: During the formation of normal eggs or sperm the chromosome (c) pairs are supposed to split leaving one of each in the egg/sperm. At conception the joining of egg/sperm brings together the pair & as tissue grows it has the proper number in each cell. With ds the egg has a pair of 21c and at conception a triple 21 is created. All cells derived after will have an extra 21 & become a ds child.
Rarely: Downs syndrome is usually related to a trisomy defect that develops during the initial cleavage of the cells during primary fetal development. A form can occur as a translocation that may be carried by a parent. An assumption is that the 21 chromosome may be damaged by maternal age or by some environmental factor that then results in downs syndrome. Most cases are just by chance.See 1 more doctor answer
Depends on parents: An unaffected mother or father could have a balanced (normal) set of chromasome material where a piece of one 21 chromasome is stuck on another. If the egg or sperm had the normal 21 and an extra 21piece hidden on another chromasome, they could pass it to the baby. It only takes an extra piece of 21 to cause ds. It is important to study ds to verify type, as translocation ds can recur each pregnany.See 2 more doctor answers
No autosomal: Down syndrome happens when an extra 21 chromosome is present in all the cells of the body. It happens before conception when the donor egg fails to shed one of its 21 chromosomes in the formation of the egg & the male 21 joins the female pair & creates an embryo with 3 number 21's. It has nothing to do with traits or mutations in the gene code.See 1 more doctor answer
Many: Increased incidence of congenital heart disease, gastrointestinal problems such as atresia and hirschsprung's, nutrition with gasroesophageal reflux and aspiration, hypo or hyperthyroidism, and neurologic; mental retardation, joint laxity and hypotonia. Some down syndrome have few problems, and some many problems.
Old world term: Before the chromosome defect was found in '60's, the the facial structure of down syndrome kids/adults, reminded folks of the features of mongolian race. Original scientific publications used that terminology. It was well into the '70's before the descriptions began to change ; the public began to use the term down syndrome exclusively.
Before/after birth?: There are a variety of screening or confirmatory tests that can be done during pregnancy. After birth, many physical features are suggestive of the diagnosis, but the physician involved would order a chromosome test to confirm or exclude the issue. Over the years, some had signs so mild many would miss the diagnosis. Others looked so different I didn't believe it.
Extra 21 chromosome: The majority of down syndrome develops when the fertilized egg gets an extra number 21 chromosome from the mother. When that cell divides and forms an embryo, every one of the cells in the baby's body have that extra 21 chromosome. There are rare cases where a baby inherits an extra part of the 21 chromosome from one of it's parents. The extra genes on the 21 chromosome cause the down syndrome.
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