Clinical Report: Hereditary Thrombotic Thrombocytopenic Purpura in a Child
Overview
This case study presents a 22-month-old girl diagnosed with hereditary thrombotic thrombocytopenic purpura (hTTP) after being misdiagnosed with immune thrombocytopenia (ITP) for over a year. The diagnosis was confirmed through targeted genetic testing, revealing compound heterozygous ADAMTS13 variants and significantly diminished enzyme activity.
Background
Hereditary thrombotic thrombocytopenic purpura (hTTP) is a rare genetic disorder characterized by severe deficiency of the ADAMTS13 protease, leading to thrombocytopenia and microthrombus formation. Accurate diagnosis is crucial, as hTTP can present atypically in children, often mimicking immune thrombocytopenia (ITP), which can delay appropriate treatment. Whole-exome sequencing (WES) has limitations in detecting exon-level copy number variations and certain frameshift variants, which can lead to misdiagnosis.
Data Highlights
No numerical data or trial data presented in the article.
Key Findings
The patient exhibited isolated severe thrombocytopenia with a nadir platelet count of 6 × 10⁹/L.
Initial whole-exome sequencing yielded negative results for pathogenic variants.
Functional analysis showed severely diminished ADAMTS13 activity at 0.23%.
Clinical Implications
For children with unexplained recurrent thrombocytopenia and a suggestive family history, it is critical to perform ADAMTS13 functional assessment and targeted genetic sequencing promptly.
Conclusion
This case highlights the importance of recognizing atypical presentations of hTTP in pediatric patients and the limitations of WES in diagnosing genetic disorders.
