A genetic analysis of autoinflammatory diseases

Autoinflammatory diseases, also known as hereditary periodic fever syndromes which are characterized by symptoms such as recurrent fever, rash, serositis, lymphadenopathy and arthritis allowed by dysregulation of innate immune system. Absence of autoreactive T cells and lack of autoantibodies production in the pathogenesis cause proinflammatory condition resulting in activation of inflammasome. Some of autoinflammatory syndromes having similar clinical findings are inherited as an autosomal dominant wheares others autosomal recessive. These autoinflammatory diseases usually have an early onset in childhood. The concept of diseases first described by McDermott et al in 1999. Since then, disease related 25 gene regions have published in INFEVERS database. Familial Mediterranean fever (FMF), TNF-receptor-associated periodic syndrome (TRAPS), Cryopyrin associated autoinflammatory syndromes (CAPS), hyperimmunoglobulinemia-D with periodic fever syndrome (HIDS), neonatal onset multisystem inflammatory disorder/ chronic infantile neurological cutaneous and articular syndrome (NOMID/CINCA), familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS), Blau sendromu (BS), Majeed syndrome (MS) and pyogenic arthritis, pyoderma gangrenosum a acne (PAPA) syndromehave been grouped as monogenic disorders. Clinical diagnosis can be difficult in cases where there are similar clinical manifestations. Most of the times definite diagnosis requires genetic testing, which also provides a better understanding of the molecular mechanisms and theurapatic interventions. In this purposes, commonly seen 131 clinically not-definitive autoinflammatory disorders patients from our region were analysed for genetic mutations. The clinical sample were provided from Departments of Internal Medicine, and Pediatric Rheumatology Clinics mainly from Cerrahpasa Medical Faculty. Blood samples were collected after ethics committee approval and written informed consent from each individual participating in this study were obtained. Spesific exon regions for the known genes were amplified by polymerase chain reactions (PCR) after genomic DNA isolation from 2 cc of blood sample for each patient. PCR products were examined through Sanger sequencing after purification. Genetic analysis were applied for FMF, TNFRSF1A, NLRP3, MVK, NOD2, CECR1, NLRP12, PSTPIP1, LPIN2 and IL1RN in individual genes or in combination of more than one gene based on the clinical information. Further next generation sequencing (NGS) using Illumina and IONS5 platforms were applied in selected genes coding regions in a subset of 43 patients and compared with Sanger sequencing results. Sanger sequencing results correlated with Miseq sequence analysis in 11 patients in our cohort. However more detailed IONS sequencing in a 15 gene panel revealed more information. As a result we have identified E943G, V928I on NOD2 gene; G144V, V325I on MVK gene; R262H, R253W on TMEM173 gene; R253Q on PSTPIP1 gene; H244R, I671V on PLCG2 gene; R189W, E185K, R862W on CARD14 gene; E601K, P626S on LPIN2 gene; F402L on NLRP12 gene; L281P on SLC29A3 gene; R261W, S420L, R159G on IL10R gene; C890R, A160T on NLRC4 gene in autoinflammatory disorders, which clarified definitive diagnosis and therapeutic interventions. As a conclusion use of NGS with a wide panel of relevant genes in comparison of to Sanger sequencing for known exons, increased the definitive diagnosis 3% to 25% in TRAPS, 23% to 50% in HIDS and 24% to 33% in ADA2 deficiency patients.