Open AccessCombined study of ADAMTS 13 and complement genes in the diagnosis of thrombotic microangiopathies using next‐generation sequencing
Author(s) -
Fidalgo Teresa,
Martinho Patrícia,
Pinto Catarina S.,
Oliveira Ana C.,
Salvado Ramon,
Borràs Nina,
Coucelo Margarida,
Manco Licínio,
Maia Tabita,
Mendes M. João,
Del Orbe Barreto Rafael,
Corrales Irene,
Vidal Francisco,
Ribeiro M. Letícia
Publication year - 2017
Publication title -
research and practice in thrombosis and haemostasis
Language(s) - English
Resource type - Journals
ISSN - 2475-0379
DOI - 10.1002/rth2.12016
Subject(s) - adamts13 , thrombotic microangiopathy , atypical hemolytic uremic syndrome , thrombotic thrombocytopenic purpura , eculizumab , medicine , immunology , exome sequencing , microangiopathic hemolytic anemia , compound heterozygosity , complement system , gene , genetics , phenotype , biology , disease , antibody , platelet
Essentials The differential diagnosis of acute thrombotic microangiopathy (TMA) is challenging. To the ADAMTS 13 activity < or >10% was added a next‐generation sequencing (NGS) gene panel. The ADAMTS13 mutation p.Cys754Arg was frequent in hereditary thrombotic thrombocytopenic purpura. We identified novel complement gene mutations and this procedure improved our diagnostic strategy.Background The 2 main forms of thrombotic microangiopathy ( TMA ) are thrombotic thrombocytopenic purpura ( TTP ) and atypical hemolytic uremic syndrome ( aHUS ). Deficiency of ADAMTS 13 and dysregulation of the complement pathway result in TTP and aHUS , respectively; however, overlap of their clinical characteristics makes differential diagnosis challenging. Objectives and Methods We aimed to develop a TMA diagnosis workflow based on ADAMTS 13 activity and screening of ADAMTS13 and complement genes using a custom next‐generation sequencing ( NGS ) gene panel. Patients For this, from a cohort of 154 Portuguese patients with acute TMA , the genotype‐phenotype correlations were analyzed in 7 hereditary TTP ( ADAMTS 13 activity <10%, no inhibitor), 36 acquired TTP ( ADAMTS 13 activity <10%, presence of an inhibitor), and in 34 presumable aHUS . Results In total, 37 different rare variants, 8 of which novel (in ADAMTS13 , CFH , and CD46 ), were identified across 7 genes. Thirteen TTP patients were homozygous (n=6), compound heterozygous (n=2), and heterozygous (n=5) for 11 ADAMTS13 variants (6 pathogenic mutations). Among the 34 aHUS patients, 17 were heterozygous for 23 variants in the different complement genes with distinct consequences, ranging from single pathogenic mutations associated with complete disease penetrance to benign variants that cause aHUS only when combined with other variants and/or CFH and CD46 risk haplotypes or CFHR1‐3 deletion. Conclusions Our study provides evidence of the usefulness of the NGS panel as an excellent technology that enables more rapid diagnosis of TMA , and is a valuable asset in clinical practice to discriminate between TTP and aHUS .