Journal of Hematology, ISSN 1927-1212 print, 1927-1220 online, Open Access
Article copyright, the authors; Journal compilation copyright, J Hematol and Elmer Press Inc
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Case Report

Volume 10, Number 3, June 2021, pages 130-135

A Case Series of TERC Variant Telomere Biology Disorders in Unrelated Families From Atlantic Canada

Figures

Figure 1.
Figure 1. Pedigree of family A. Roman numerals indicate generations and arabic numbers indicate individuals. The proband is indicated by an arrow. The individuals who are heterozygous for the TERC n.107G>T are marked with a +. Individual(s) who were tested for TERC n.107G>T and did not have the variant (wild type) are marked with a -. Phenotypes are represented by the following colors: red signifies solid organ malignancy, blue signifies cytopenia and green signifies myelodysplastic syndrome.
Figure 2.
Figure 2. Pedigree of family B. Roman numerals (I-IV) indicate generations and arabic numbers indicate individuals. The proband is indicated by an arrow. The individual(s) who are heterozygous for the TERC n.437T>G are marked with a +. Phenotypes are represented by the following colors: red signifies solid organ malignancy, blue signifies pulmonary fibrosis and green signifies aplastic anemia.

Table

Table 1. Summary of Phenotypic Characteristics and Relevant Diagnostic Investigations in the Individuals From Families A and B
 
Phenotypic characteristics suggestive of TBDsAge at diagnosisCBC at time of diagnosisBone marrow biopsyTelomere length (TL)TERC variant (NR 001566.1)
ANC: absolute neutrophil count; HGB: hemoglobin; MCV: mean corpuscular volume; N/A: not applicable; PLT: platelets; WBC: white blood cell count; TBDs: telomere biology disorders.
Proband A (A III-1)Early graying of hair, myelodysplastic syndrome19HGB 82 g/L (MCV 113), PLT 59 × 109/L, WBC 8.9 × 109/L (ANC 6.37)Multilineage dysplasia, 1% blasts, normal cytogeneticsTL less than the first percentile for age for total lymphocytes and all lymphocyte subsetsTERC n.107G>T (heterozygous)
Proband A’s eldest daughter (A IV-1)NoneN/AHGB 149 g/L, PLT 245 × 109/L, WBC 6.21 × 109/LNot performedTL within normal limitsWild type
Proband A’s son (A IV-2)None11HGB 128 g/L (MCV 95.6), PLT 160 × 109/L, WBC 3.42 × 109/L (ANC 1.54)Overall unremarkable including no dysplasia, no increase in blasts and normal cytogeneticsTL less than the first percentile for age for total lymphocytes and all lymphocyte subsetsTERC n.107G>T (heterozygous)
Proband A’s youngest daughter (A IV-3)Pre-term birth, dental carries10HGB 128 g/L (MCV 101.1), PLT 35 × 109/L, WBC 4.36 × 109/L (ANC 2.03)Rare dysplastic erythroblasts and megakaryocytes but overall, no significant abnormalityTL less than the first percentile for age for total lymphocytes and all lymphocyte subsetsTERC n.107G>T (heterozygous)
Proband B (B III-2)Pulmonary fibrosis, premature graying of hair35 (aplastic anemia); 36 (pulmonary fibrosis)HGB 124 g/L (MCV 104.5), PLT 95 × 109/L, WBC 5.01 × 109/L (ANC 3.52)Markedly hypocellular marrow (20-30% cellularity) with decrease trilineage hematopoiesis and no dysplastic changes, no increase in blastsLength less than the first percentile for age for total lymphocytes and all lymphocyte subsetsTERC n.437T>G (heterozygous)