Epigenetic differences arise during the lifetime of monozygotic twins.
Monozygous twins share a common genotype. However, most monozygotic twin pairs are not identical; several types of phenotypic discordance may be observed, such as differences in susceptibilities to disease and a wide range of anthropomorphic features. There are several possible explanations for these observations, but one is the existence of epigenetic differences. To address this issue, we examined the global and locus-specific differences in DNA methylation and histone acetylation of a large cohort of monozygotic twins. We found that, although twins are epigenetically indistinguishable during the early years of life, older monozygous twins exhibited remarkable differences in their overall content and genomic distribution of 5-methylcytosine DNA and histone acetylation, affecting their gene-expression portrait. These findings indicate how an appreciation of epigenetics is missing from our understanding of how different phenotypes can be originated from the same genotype.
Fraga
Mario F
MF
Epigenetics Laboratory, Spanish National Cancer Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain.
Ballestar
Esteban
E
Paz
Maria F
MF
Ropero
Santiago
S
Setien
Fernando
F
Ballestar
Maria L
ML
Heine-Suñer
Damia
D
Cigudosa
Juan C
JC
Urioste
Miguel
M
Benitez
Javier
J
Boix-Chornet
Manuel
M
Sanchez-Aguilera
Abel
A
Ling
Charlotte
C
Carlsson
Emma
E
Poulsen
Pernille
P
Vaag
Allan
A
Stephan
Zarko
Z
Spector
Tim D
TD
Wu
Yue-Zhong
YZ
Plass
Christoph
C
Esteller
Manel
M
D044503:5-Methylcytosine / Q000378:metabolism; D000107:Acetylation; D000328:Adult; D000704:Analysis of Variance; D019175:DNA Methylation; D019075:Electrophoresis, Capillary; D044127:Epigenesis, Genetic / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008297:Male; D021141:Nucleic Acid Amplification Techniques; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013030:Spain; D011795:Surveys and Questionnaires; D014430:Twins, Monozygotic / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D049951:X Chromosome Inactivation / Q000235:genetics
D006657:Histones; D044503:5-Methylcytosine