Question of the Week

Question :

Posted On : 30 May 2009

What are the paediatric diseases with 100percent concordance in monozygotic twins_?

Expert Answer :

No expert answer available.

Answer Discussion :

robert newman

None other than twinning

15 years ago

shalini

genetic diseases

15 years ago

MANGESH DAMODAR KHANDAVE

AUTISM

15 years ago

pediatriconcall

Monozygotic twins, frequently referred to as identical twins, occur when a single egg is fertilized to form one zygote {monozygotic} which then divides into two separate embryos. They are the same sex and their traits and physical appearances are very similar but not exactly the same` although they have nearly identical DNA. Monozygotic twins are genetically identical {unless there has been a mutation in development} and they are always the same sex. On rare occasions, monozygotic twins may express different phenotypes, normally due to an environmental factor or the deactivation of different X chromosomes in monozygotic female twins, and in some extremely rare cases, due to aneuploidy, twins may express different sexual phenotypes, normally due to an XXY Klinefelter`s syndrome zygote splitting unevenly. Monozygotic twins have nearly identical DNA, but differing environmental influences throughout their lives affect which genes are switched on or off. This is called epigenetic modification. A study of 80 pairs of human twins ranging in age from three to 74 showed that the youngest twins have relatively few epigenetic differences. The number of epigenetic differences between MZ twins increases with age. Fifty-year-old twins had over three times the epigenetic difference of three-year-old twins. Thus disease phenotype of genetic diseases may vary.

15 years ago

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