Family pedigree and telomere length measurements of patient with Hoyeraal-Hreidarsson syndrome. (A) Pedigree of family in which the proband has compound heterozygous variants in TERT. Amino acid changes resulting from the TERT variants are labeled in blue. Arrow and black shaded box indicate the proband with Hoyeraal-Hreidarsson syndrome; gray shading indicates those with mild DC features. (B) Relative telomere length (as a percentage of that of the control 4n cell line CCRF-CEM) according to age, measured by Flow-FISH. Lines represent the 1st, 10th, 50th, 90th, and 99th percentiles of telomere length of 240 healthy controls. (C) Relative telomere length according to age, measured by qPCR. Lines represent the 1st, 10th, 50th, 90th, and 99th percentiles of telomere length of 240 healthy controls. (D) Telomere length in the proband and his parents, measured by Southern blot analysis with a probe against telomeric DNA.