Just because you have a gene, doesn’t mean it’s actually active. They can sit there dormant for your entire life, or pop up later in life as well.
Interestingly, telomeres can suppress genes that are close to it. As telomeres shorten however, gene can begin to express themselves.
Such seems to be the case with facioscapulohumeral muscular dystrophy (FSHD).
The Scientist reports:
“DUX4, a gene responsible for the genetic disease facioscapulohumeral muscular dystrophy (FSHD), is normally silenced because it sits next to a telomere—a protective DNA sequence that caps the ends of chromosomes, according to a study published today (May 5) in Nature Structural and Molecular Biology. But as telomeres shorten, as they do with age, DUX4 expression climbs, which may explain the late onset of FSHD.”
This is quite interesting, as this may be one of the reasons that telomere length seems to have such a profound effect on age.
Guido Stadler at the University of Texas Southwestern Medical Center in Dallas, co-author of the study was quite surprised at this result, going as far as to say,
“This was completely unexpected,” “We think that DUX4 and FRG2 are the tip of an iceberg,” “This represents a very significant general advance in our understanding of how telomere shortening may affect human biology.”