engleski

Periodic fever syndrome with novel TRNT1 variant - possible cause of TRNT1 deficiency or just an incidental finding?

Introduction: Biallelic pathogenic variants in TRNT1 gene, coding for the enzyme transfer RNA nucleotidyltransferase 1, cause TRNT1 deficiency with various clinical manifestations of autoinflammation, autoimmunity and immunodeficiency, including the syndrome of congenital sideroblastic anaemia with immunodeficiency, periodic fevers and developmental delay (SIFD). Objectives: Authors present a case of a child with recurrent fevers and epilepsy with de novo heterozygous mutation in TRNT1 gene of uncertain role in disease pathogenesis, successfully treated with TNFα inhibitor. Methods: Retrospective analysis of patient medical data and genomic testing using whole exome sequencing (WES). Results: Three months old female infant was referred to our Department with right-sided hemiconvulsions and dysrhythmic EEG changes treated with valproic acid. Subsequently, she had seizures on several occasions successfully treated with diazepam. Since 11 months of age, the child has had periodic protracted febrile episodes. Seven months after the onset of fever, she developed intermittent erythema accompanied with swelling of both hands, feet, knees and face. Subsequently, episodes of fever recurred in an irregular rhythm. The patient has been showing signs of progressive fatigue and severe facial erythema unrelated to febrility. Her physical exam was unremarkable apart from occasional facial erythema. Laboratory findings were normal, except for the long-lasting microcytic anemia (the lowest hemoglobin was 85 g/L) and elevated C-reactive protein and erythrocyte sedimentation rate during the febrile episodes. Comprehensive laboratory, microbiological and immunological examination failed to establish underlying diagnosis. Bone marrow examinations were normal. The frequent and prolonged febrile episodes were successfully treated with short- term methylprednisolone, however this treatment failed to prevent the occurrence of new episodes. To ameliorate fevers, TNFα inhibitor (etanercept) was consequently introduced in therapy at 5 years of age. Over the four month period after the initiation of TNFα inhibitor, the child had no further febrile episodes or seizures and there was an improvement in appetite and general condition. It is planned to reduce the dose of antiepileptics. Genomic testing using trio WES identified a de novo heterozygous TRNT1 variant, NM_182916.2 (TRNT1_v001): c.448C>T, p.(R150C), predicted to be pathogenic with high CADD score. Previous cases of TRNT1 deficiency have been described with bialellic TRNT1 pathogenic variants and analyses are underway to elucidate whether this finding could establish the underlying diagnosis. At present we hypothesize that this could be a case of unidentified second intronic TRNT1 variant or that this TRNT1 variant could have a dominant negative effect. In this respect, it should be noted that in our patient we have identified some but not other features of SIFD. Conclusion: Clinical manifestations associated with TRNT1 deficiency have a broad spectrum with significant clinical heterogeneity, which makes it difficult for rapid clinical recognition. Although the WES is as a powerful tool for the diagnosis of clinically unrecognized genetic conditions, there are still unresolved cases that pose a challenge in routine clinical practice.

TRNT1 deficiency ; periodic fever syndrome ; whole exome sequencing

Objavljeno u Pediatric Rheumatology 2019, 17(Suppl 1):P2128