Systemic inflammatory syndrome in children with FARSA deficiency

Pulmonary fibrosis may begin in infancy: from childhood to adult interstitial lung disease

BACKGROUND

Childhood interstitial lung disease (chILD) encompasses a group of rare heterogeneous respiratory conditions associated with significant morbidity and mortality. Reports suggest that many patients diagnosed with chILD continue to have potentially progressive or fibrosing disease into adulthood. Over the last decade, the spectrum of conditions within chILD has widened substantially, with the discovery of novel entities through advanced genetic testing. However, most evidence is often limited to small case series, with reports disseminated across an array of subspecialty, clinical and molecular journals. In particular, the frequency, management and outcome of paediatric pulmonary fibrosis is not well characterised, unlike in adults, where clear diagnosis and treatment guidelines are available.

METHODS AND RESULTS

This review assesses the current understanding of pulmonary fibrosis in chILD. Based on registry data, we have provisionally estimated the occurrence of fibrosis in various manifestations of chILD, with 47 different potentially fibrotic chILD entities identified. Published evidence for fibrosis in the spectrum of chILD entities is assessed, and current and future issues in management of pulmonary fibrosis in childhood, continuing into adulthood, are considered.

CONCLUSIONS

There is a need for improved knowledge of chILD among pulmonologists to optimise the transition of care from paediatric to adult facilities. Updated evidence-based guidelines are needed that incorporate recommendations for the diagnosis and management of immune-mediated disorders, as well as chILD in older children approaching adulthood.

Development of Collateral Vessels after Anterior Circulation Large Vessel Occlusion in Pediatric Arterial Ischemic Stroke Relates to Stroke Etiology: A Longitudinal Study

BACKGROUND AND PURPOSE

The characteristics of large vessel occlusion (LVO) in the acute phase of pediatric arterial ischemic stroke and their natural history according to stroke etiology are poorly explored. This studied aimed at describing the prevalence and the radiological evolution of LVO in pediatric AIS.

MATERIALS AND METHODS

This single-center retrospective study included consecutive non-neonate children with acute arterial ischemic stroke, intracranial proximal LVO in the anterior circulation (MCA, anterior cerebral artery, and/or ICA), and clinical and imaging follow-up for at least 18 months, during a 9-year period.

RESULTS

Intracranial LVO was observed in 24.8% of patients with anterior circulation arterial ischemic stroke and adequate follow-up (n = 26/105), with a median age of 4.2 years (IQR 0.8-9), sex ratio 1.16. The main stroke etiology associated with LVO was unilateral focal cerebral arteriopathy (n = 12, 46%). During follow-up, a specific pattern of unilateral poststroke anastomotic bridge was observed in 8/26 patients, with the poststroke development of nonperforating collaterals forming a bridge in bypass of the LVO site with visible distal flow, within a median delay of 11 months. The development of unilateral poststroke anastomotic bridge was only observed in patients with unilateral focal cerebral arteriopathy. No patient with this pattern experienced stroke recurrence or further progressive vascular modifications.

CONCLUSIONS

After stroke, the development of unilateral poststroke anastomotic bridge is specifically observed in children with focal cerebral arteriopathy, appearing in the first year after stroke. This clinical-radiologic pattern was not associated with stroke recurrence or arterial worsening, differentiating it from progressive intracranial arteriopathy, such as Moyamoya angiopathy.

[Lung involvement in autoinflammatory diseases]

Genetic autoinflammatory diseases are now a recognized and rapidly expanding group. The lung involvement historically associated with autoinflammatory diseases is inflammatory seritis, primarily seen in familial Mediterranean fever and other interleukin-1 mediated diseases. Over the last ten years, pulmonary involvement has been the core presentation of two autoinflammatory diseases associated with constitutive type I interferon activation, i.e. SAVI and COPA syndrome. Most patients with these diseases usually develop early progression to pulmonary fibrosis, which is responsible for high rates of morbidity and mortality. Other rare autoinflammatory diseases are associated with alveolar proteinosis, particularly when related to MARS mutations. Additionally, in adults, VEXAS is frequently associated with pulmonary involvement, albeit without prognosis effect. A molecular approach to autoinflammatory diseases enables not only the definition of biomarkers for diagnosis, but also the identification of targeted treatments. Examples include JAK inhibitors in SAVI and COPA syndrome, even though this therapy does not prevent progression to pulmonary fibrosis. Another illustrative example is the efficacy of methionine supplementation in alveolar proteinosis linked to MARS mutations. Overall, in autoinflammatory diseases the lung is now emerging as a possible affected organ. Continuing discovery of new autoinflammatory diseases is likely to uncover further pathologies involving the lung. Such advances are expected to lead to the development of novel therapeutic perspectives.

Phenylalanyl-tRNA synthetase deficiency caused by biallelic variants in FARSA gene and literature review

BACKGROUND

Aminoacyl-tRNA synthetases (ARSs) are indispensable enzymes for protein biosynthesis in cells. The phenylalanyl-tRNA synthetase (FARS1) located in cytoplasm which consists of two FARS alpha subunits (FARSA) and two FARS beta subunits (FARSB). Autosomal recessive inheritance of pathogenic variants of FARSA or FARSB can result in defective FARS1 which are characterized by interstitial lung disease, liver disease, brain abnormalities, facial dysmorphism and growth restriction.

METHODS

Exome sequencing was used to detect the candidate variants. The in silico prediction and expressional level analysis were performed to evaluate the pathogenicity of the variations. Additionally, we presented the patient's detailed clinical information and compared the clinical feature with other previously reported patients with FARSA-deficiency.

RESULTS

We identified compound heterozygous rare missense variants (c.1172 T > C/ p.Leu391Pro and c.1211G > A/ p.Arg404His) in FARSA gene in a Chinese male patient. The protein structure prediction and the analysis of levels of FARSA and FARSB subunits indicated both variants pathogenic. Clinical feature review indicated inflammatory symptoms in young infants may be an additional key feature. Thyroid dysfunction should be considered as a phenotype with variable penetrance.

CONCLUSIONS

Our results expanded the current phenotypic and genetic spectrum of FARSA-deficiency.

Fatal systemic disorder caused by biallelic variants in FARSA

Background

Aminoacyl tRNA transferases play an essential role in protein biosynthesis, and variants of these enzymes result in various human diseases. FARSA, which encodes the α subunit of cytosolic phenylalanyl-tRNA synthetase, was recently reported as a suspected causal gene for multiorgan disorder. This study aimed to validate the pathogenicity of variants in the FARSA gene.

Results

Exome sequencing revealed novel compound heterozygous variants in FARSA, P347L and R475Q, from a patient who initially presented neonatal-onset failure to thrive, liver dysfunction, and frequent respiratory infections. His developmental milestones were nearly arrested, and the patient died at 28 months of age as a result of progressive hepatic and respiratory failure. The P347L variant was predicted to disrupt heterodimer interaction and failed to form a functional heterotetramer by structural and biochemical analyses. R475 is located at a highly conserved site and is reported to be involved in phenylalanine activation and transfer to tRNA. The R475Q mutant FARSA were co-purified with FARSB, but the mutant enzyme showed an approximately 36% reduction in activity in our assay relative to the wild-type protein. Additional functional analyses on variants from previous reports (N410K, F256L, R404C, E418D, and F277V) were conducted. The R404C variant from a patient waiting for organ transplantation also failed to form tetramers but the E418D, N410K, F256L, and F277V variants did not affect tetramer formation. In the functional assay, the N410K located at the phenylalanine-binding site exhibited no catalytic activity, whereas other variants (E418D, F256L and F277V) exhibited lower ATPase activity than wild-type FARSA at low phenylalanine concentrations.

Conclusions

Our data demonstrated the pathogenicity of biallelic variants in FARSA and suggested the implication of hypomorphic variants in severe phenotypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02457-9.