“CHildren with Inherited Platelet disorders Surveillance” (CHIPS) retrospective and prospective observational cohort study by Italian Association of Pediatric Hematology and Oncology (AIEOP)

Abstract

BackgroundInherited thrombocytopenias (ITs) are rare congenital bleeding disorders characterized by different clinical expression and variable prognosis. ITs are poorly known by clinicians and often misdiagnosed with most common forms of thrombocytopenia.Material and methods“CHildren with Inherited Platelet disorders Surveillance” study (CHIPS) is a retrospective – prospective observational cohort study conducted between January 2003 and January 2022 in 17 centers affiliated to the Italian Association of Pediatric Hematology and Oncology (AIEOP). The primary objective of this study was to collect clinical and laboratory data on Italian pediatric patients with inherited thrombocytopenias. Secondary objectives were to calculate prevalence of ITs in Italian pediatric population and to assess frequency and genotype–phenotype correlation of different types of mutations in our study cohort.ResultsA total of 139 children, with ITs (82 male - 57 female) were enrolled. ITs prevalence in Italy ranged from 0.7 per 100,000 children during 2010 to 2 per 100,000 children during 2022. The median time between the onset of thrombocytopenia and the diagnosis of ITs was 1 years (range 0 - 18 years). A family history of thrombocytopenia has been reported in 90 patients (65%). Among 139 children with ITs, in 73 (53%) children almost one defective gene has been identified. In 61 patients a pathogenic mutation has been identified. Among them, 2 patients also carry a variant of uncertain significance (VUS), and 4 others harbour 2 VUS variants. VUS variants were identified in further 8 patients (6%), 4 of which carry more than one variant VUS. Three patients (2%) had a likely pathogenic variant while in 1 patient (1%) a variant was identified that was initially given an uncertain significance but was later classified as benign. In addition, in 17 patients the genetic diagnosis is not available, but their family history and clinical/laboratory features strongly suggest the presence of a specific genetic cause. In 49 children (35%) no genetic defect were identified. In ninetyseven patients (70%), thrombocytopenia was not associated with other clinically apparent disorders. However, 42 children (30%) had one or more additional clinical alterations.ConclusionOur study provides a descriptive collection of ITs in the pediatric Italian population.

State-of-the-Art Targeted High-Throughput Sequencing for Detecting Inherited Platelet Disorders

“…40 In the recently performed "Children with Inherited Platelet disorder Surveillance" study (CHIPS), in which 139 children with inherited thrombocytopenias were enrolled, the defective genetic locus could be identified in only 73 children (53%). 41 These low detection rates may reflect the fact that there is currently a lack of knowledge about all genes involved in the regulation of platelet production and function, and that other causative defects in noncoding genomic regions or in acquired gene defects for IPDs are overlooked by panel sequencing. One successful strategy for identifying new IPD disease genes, as well as for molecular diagnosis in established IPD genes, involves whole exome or whole genome sequencing, especially when combined with other selective approaches (e.g., with combined segregation analysis by Sanger sequencing) or complementary functional studies to ensure clinical relevance.…”