Telomere length analysis using qPCR in aplastic anemia: prevalence and predictive value for germline mutation status

Telomere length analysis (TLA) is used to identify telomere biology disorders (TBD) in aplastic anemia (AA); however, the diagnostic performance of quantitative PCR (qPCR)-based TLA across germline mutation categories remains poorly defined. A total of 305 consecutive patients with AA were prospectively enrolled over 3.5 years. All patients underwent age-adjusted qPCR-based TLA and comprehensive germline sequencing, including whole exome sequencing or blended genome-exome sequencing, and were classified as having inherited bone marrow failure syndrome (IBMFS) (Category 1, n = 40), a monoallelic carrier state (Category 2, n = 19), a variant of uncertain significance (VUS; Category 3, n = 39), or AA without germline variants (Category 4, n = 207). Shortened telomere length (TL) (≤ 10th percentile) was present in 37.7% of patients, and very short TL (≤ 1st percentile) was present in 14.8%. The degree of shortening varied by etiology: 71.4% of confirmed TBD gene carriers had shortened TL compared with 31.6% of carriers of biallelic variants in Fanconi anemia pathway genes and 37.7% of patients with acquired AA. TL did not distinguish confirmed IBMFS from acquired AA across the full disease spectrum; however, normal TL (> 10th percentile) excluded TBD-associated IBMFS (TBD-IBMFS) with a negative predictive value of 98.5%. Very short TL (≤ 1st percentile) had a positive predictive value of only 12.9% for TBD-IBMFS and was also observed in 13.0% of acquired-AA patients. In unselected patients with AA, qPCR-based TLA does not distinguish inherited from acquired disease across the full spectrum of IBMFS; however, normal TL substantially lowers the likelihood of TBD-IBMFS. Very short TL is not specific to constitutional telomeropathy and should be interpreted with caution when adjudicating TBD variants of uncertain significance.