Targeted high-throughput sequencing for genetic diagnostics of hemophagocytic lymphohistiocytosis

• Published in: Genome medicine Vol. 7; no. 130; p. 130
• Main Authors: Tesi, Bianca, Lagerstedt-Robinson, Kristina, Chiang, Samuel C C, Ben Bdira, Eya, Abboud, Miguel, Belen, Burcu, Devecioglu, Omer, Fadoo, Zehra, Yeoh, Allen E J, Erichsen, Hans Christian, Möttönen, Merja, Akar, Himmet Haluk, Hästbacka, Johanna, Kaya, Zuhre, Nunes, Susana, Patiroglu, Turkan, Sabel, Magnus, Saribeyoglu, Ebru Tugrul, Tvedt, Tor Henrik, Unal, Ekrem, Unal, Sule, Unuvar, Aysegul, Meeths, Marie, Henter, Jan-Inge, Nordenskjöld, Magnus, Bryceson, Yenan T
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 18-12-2015; BioMed Central
• Subjects: Adolescent; Adult; adult-onset; Age of Onset; Aged; Analysis; Base Sequence; chediak-higashi-syndrome; Child; Child, Preschool; Clinical Medicine; Cohort Studies; deficiency; DNA sequencing; Female; Genetic Predisposition to Disease; Genetic Testing; Genetics & Heredity; Genomes; Genomics; griscelli syndrome type-2; Humans; immunodeficiencies; Infant; Infant, Newborn; Klinisk medicin; Lymphohistiocytosis, Hemophagocytic - diagnosis; Lymphohistiocytosis, Hemophagocytic - genetics; Male; Medicin och hälsovetenskap; Middle Aged; munc13-4; Mutation; Nucleotide sequencing; perforin; primary; Prospective Studies; protein; rab27a mutations; Sequence Analysis, DNA; t-cell; Young Adult
• ISSN: 1756-994X; 1756-994X
• DOI: 10.1186/s13073-015-0244-1

Hemophagocytic lymphohistiocytosis (HLH) is a rapid-onset, potentially fatal hyperinflammatory syndrome. A prompt molecular diagnosis is crucial for appropriate clinical management. Here, we validated and prospectively evaluated a targeted high-throughput sequencing approach for HLH diagnostics.
A high-throughput sequencing strategy of 12 genes linked to HLH was validated in 13 patients with previously identified HLH-associated mutations and prospectively evaluated in 58 HLH patients. Moreover, 2504 healthy individuals from the 1000 Genomes project were analyzed in silico for variants in the same genes.
Analyses revealed a mutation detection sensitivity of 97.3%, an average coverage per gene of 98.0%, and adequate coverage over 98.6% of sites previously reported as mutated in these genes. In the prospective cohort, we achieved a diagnosis in 22 out of 58 patients (38%). Genetically undiagnosed HLH patients had a later age at onset and manifested higher frequencies of known secondary HLH triggers. Rare, putatively pathogenic monoallelic variants were identified in nine patients. However, such monoallelic variants were not enriched compared with healthy individuals.
We have established a comprehensive high-throughput platform for genetic screening of patients with HLH. Almost all cases with reduced natural killer cell function received a diagnosis, but the majority of the prospective cases remain genetically unexplained, highlighting genetic heterogeneity and environmental impact within HLH. Moreover, in silico analyses of the genetic variation affecting HLH-related genes in the general population suggest caution with respect to interpreting causality between monoallelic mutations and HLH. A complete understanding of the genetic susceptibility to HLH thus requires further in-depth investigations, including genome sequencing and detailed immunological characterization.