Telomere lengths in patients with DC and first-degree family members. (A) Patients with DC due to a TERC gene mutation. (B) Patients with DC due to a TERT gene mutation. (C) Patients with DC due to a DKC1 gene mutation. People with signs of BMF are shown in black; family members without BMF are shown in gray. Heterozygous mutation carriers are indicated with a half-filled symbol; filled symbol indicates homozygosity (hemizygosity/compound heterozygosity) for the mutation. (D) Telomere length in 41 subjects with a de novo TERT gene deletion due to a chromosome deletion syndrome that includes the TERT gene (5p- syndrome).³⁵