Mutations in dyskeratosis congenita: their impact on telomere length and the diversity of clinical presentation.
The two genes mutated in the bone marrow failure syndrome dyskeratosis congenita (DC) both encode components of the telomerase complex responsible for maintaining the ends of chromosomes in stem cells and in the germ line. In reviewing the mutation profile that is found in DC, we describe 9 novel mutations in the DKC1 gene and 3 novel TERC mutations responsible for the X-linked and autosomal dominant forms of the disease, respectively, but find that two thirds of the families do not have mutations in either of these genes. In a significant subset of these uncharacterized families, the index case presents with severe disease previously defined as the Hoyeraal Hreidarsson (HH) syndrome. The diverse clinical phenotype seen in patients with X-linked DC is not explained by the different amino acid substitutions: Presentation of the recurrent A353V substitution ranges from classic DC to the severe HH variant. However, we do see that patients with HH have significantly shorter telomeres than those with a relatively mild presentation. In the new families described with TERC mutations, there is further evidence of disease anticipation associated with shorter telomeres in the younger generations. This study highlights the considerable genetic and phenotypic diversity of DC.
Vulliamy
Tom J
TJ
Department of Haematology, Hammersmith Hospital, Du Cane Rd, London, W12 ONN, United Kingdom. t.vulliamy@imperial.ac.uk
Marrone
Anna
A
Knight
Stuart W
SW
Walne
Amanda
A
Mason
Philip J
PJ
Dokal
Inderjeet
I
D041321:Chromosomes, Human, X; D019871:Dyskeratosis Congenita / Q000235:genetics*; D005260:Female; D005799:Genes, Dominant; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008958:Models, Molecular; D009154:Mutation; D012313:RNA / Q000737:chemistry / Q000235:genetics*; D035781:Siblings; D019098:Telomerase / Q000737:chemistry / Q000235:genetics*; D016615:Telomere / Q000235:genetics* / Q000648:ultrastructure
C422952:telomerase RNA; D012313:RNA; D019098:Telomerase