NHLRC2 variants identified in patients with fibrosis, neurodegeneration, and cerebral angiomatosis (FINCA): characterisation of a novel cerebropulmonary disease
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A novel multi-organ disease that is fatal in early childhood was identified in three patients from two non-consanguineous families. These children were born asymptomatic but at the age of 2 months they manifested progressive multi-organ symptoms resembling no previously known disease. The main clinical features included progressive cerebropulmonary symptoms, malabsorption, progressive growth failure, recurrent infections, chronic haemolytic anaemia and transient liver dysfunction. In the affected children, neuropathology revealed increased angiomatosis-like leptomeningeal, cortical and superficial white matter vascularisation and congestion, vacuolar degeneration and myelin loss in white matter, as well as neuronal degeneration. Interstitial fibrosis and previously undescribed granuloma-like lesions were observed in the lungs. Hepatomegaly, steatosis and collagen accumulation were detected in the liver. A whole-exome sequencing of the two unrelated families with the affected children revealed the transmission of two heterozygous variants in the NHL repeat-containing protein 2 (NHLRC2); an amino acid substitution p.Asp148Tyr and a frameshift 2-bp deletion p.Arg201GlyfsTer6. NHLRC2 is highly conserved and expressed in multiple organs and its function is unknown. It contains a thioredoxin-like domain; however, an insulin turbidity assay on human recombinant NHLRC2 showed no thioredoxin activity. In patient-derived fibroblasts, NHLRC2 levels were low, and only p.Asp148Tyr was expressed. Therefore, the allele with the frameshift deletion is likely non-functional. Development of the Nhlrc2 null mouse strain stalled before the morula stage. Morpholino knockdown of nhlrc2 in zebrafish embryos affected the integrity of cells in the midbrain region. This is the first description of a fatal, early-onset disease; we have named it FINCA disease based on the combination of pathological features that include fibrosis, neurodegeneration, and cerebral angiomatosis.
KeywordsCentral nervous system Cerebropulmonary disease Multi-organ disease Interstitial fibrosis Neurodegeneration Brain angiogenesis
The authors would like to thank Professors Eric Shoubridge, Kalervo Hiltunen and Christer Betsholtz, Assistant Professor Michael Vanlandewijck, Adjunct Professor Siri Lehtonen and Dr. Riikka Pietilä for their expert advice and support and also Ms. Pirjo Keränen, Ms. Riitta Vuento, Ms. Maarit Haarala, Ms. Hanna Seppälä, Ms. Kirsi Säkkinen, the Transgenic Core Facility at Biocenter Oulu, and the Laboratory Animal Centre at the University of Oulu for their expert assistance. Biocenter Oulu Electron Microscopy core facility, a member of Biocenter Finland, is acknowledged for their help with EM analysis. The zebrafish work was carried out at University of Tampere core facility, supported by Biocenter Finland. The digital pathology scanner of Northern Finland Biobank Borealis was used in imaging the neuropathological findings. This work was conducted with support from the Research Council for Health of the Academy of Finland (JU, decision number 138566; RH, decision numbers 266498, 273790 and 303996; MH, decision number 1126662; LR, decision numbers 266457 and 272573); the Sigrid Juselius Foundation (JU, RH and MH); the Foundation for Paediatric Research, Finland (JU and MKK); the Alma and KA Snellman Foundation (JU and MKK); a Marie Curie International Outgoing Fellowship of the European Union’s Seventh Framework Programme (Grant agreement number 273669 [BioMit]) (RH); Foundation of the Finnish Anti-Tuberculosis Association (RK); the Jane and Aatos Erkko Foundation (MR); the Competitive State Research Financing of the Expert Responsibility Area of Tampere University Hospital (MR); Special State Grants for Health Research in the Department of Paediatrics and Adolescence at Oulu University Hospital, Finland (JU); the National Heart, Lung and Blood Institute of the US National Institutes of Health under award number HL-54703 (LMN) and the Eudowood Foundation (LMN).
Compliance with ethical standards
All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Prior to the study, the guardians of the patients gave written informed consent to participate in the studies, and this was approved by the Ethics Committee of Oulu University Hospital (EETTMK 51/2008). Furthermore, the guardians of the patients in this manuscript have given written informed consent for the publication of their case details. All procedures performed in the studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted. The National Animal Experiment Board of Finland approved the study protocol (ESAVI/5882/04.10.07/2014). Animal care and experimental procedures were conducted in accordance with the national legislation and EU Directive 2010/63/EU. Zebrafish housing and maintenance were done according to facility permission ESAVI/10079/04.10.06/2015. All applicable international, national and/or institutional guidelines for the care and use of animals were followed.
Conflict of interest
The authors declare that they have no conflict of interest.
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