Respuesta :
Comparison of the lentgth of telomeres
In children, as well as the next generation of this family, the size of the telomeres will decrease proportionally to the succession of generations (due to the anticipation of the disease). Therefore telomere lengths at parents are greater than those of their children, hence the earlier onset of the disease.
Why telomeres are shorter than normal ?
Individuals with the disease have defective telomerase, and are therefore unable to synthesize telomeres. They will therefore have abnormally short telomeres and will be unable to restore a normal size of their telomeres due to insufficient telomerase activity; in this hypothesis, the shorter the telomere of the chromosomes inherited from the parent carrying the mutation, the sooner the symptoms of the disease will be declared.
Why DCK arises earlier ago in subsequent generations ?
With the succession of generations, the spermatozoa of the sick parents will not only transmit the mutation that will cause the congenital dyskeratosis, but in addition, their own telomeres are shortened. and since the cell is deficient in telomerase, the telomeres will shorten further, hence the decrease in the length of the telomeres and the evolution of the disease with the generations (anticipation).