Question

Dyskeratosis congenita (DKC) is a rare genetic disorder characterized by abnormal fingernails and skin pigmentation, the formation of white patches on the tongue and cheek, and progressive failure of the bone marrow. An autosomal dominant form of DKC results from mutations in the gene that encodes the RNA component of telomerase. Tom Vulliamy and his colleagues examined 15 families with autosomal dominant DKC (T. Vulliamy et al. 2004, Nature Genetics 36:447-449). They observed that the median age of onset of DKC in parents was 37 ears, whereas the median age of onset in the children of affected parents was 14.5 years. Thus, DKC in ese families arose at progressively younger ages in successive generations, a phenomenon known as anticipation The researchers measured telomere length of members of these families; the measurements are given in the adjoining table. Telomere length normally shortens with age, and so telomere length was adjusted for age. Note that the age-adjusted telomere length of all members of these families is negative, indicating that their telomeres are shorter than normal. For age-adjusted telomere length, the more negative the number, the shorter the telomere.

Answer 1

(2)option a is right.People with DKC shortened telomeres due to defective telomerase protein that cannot maintain the telomere structure properly.