Interstitial Lung Disease in Children With Selected Primary Immunodeficiency Disorders-A Multicenter Observational Study.

Primary immunodeficiencies (PIDs) are rare disorders of the immune system encompassing inborn errors of immunity. Primary antibody deficiencies constitute the largest group of PID with common variable immunodeficiency (CVID) being the most common symptomatic form. Combined immunodeficiencies (CID) accompanied by antibody deficiency can mimic CVID and these patients need the verification of the final diagnosis. Respiratory involvement, especially interstitial lung disease (ILD), poses a relevant cause of morbidity and mortality among patients with PID and in some cases is the first manifestation of immunodeficiency. In this study we present a retrospective analysis of a group of children with primary immunodeficiency and ILD - the clinical, radiological, histological characteristics, treatment strategies and outcomes. Eleven children with PID-related ILD were described. The majority of them presented CVID, in three patients CID was recognized. All patients underwent detailed pulmonary diagnostics. In eight of them histological analysis of lung biopsy was performed. We noted that in two out of 11 patients acute onset of ILD with respiratory failure was the first manifestation of the disease and preceded PID diagnosis. The most common histopathological diagnosis was GLILD. Among the analyzed patients three did not require any immunosuppressive therapy. All eight treated children received corticosteroids as initial treatment, but in some of them second-line therapy was introduced. The relevant side effects in some patients were observed. The study demonstrated that the response to corticosteroids is usually prompt. However, the resolution of pulmonary changes may be incomplete and second-line treatment may be necessary.

FARSA mutations mimic phenylalanyl-tRNA synthetase deficiency caused by FARSB defects.

Pathogenic variants in genes encoding aminoacyl-tRNA synthetases cause numerous disorders characterized by involvement of neurons, muscles, lungs and liver. Recently, biallelic FARSB defects have been shown to cause severe growth restriction with combined brain, liver and lung involvement (Rajab interstitial lung disease [ILD] with brain calcifications). Herein, for the first time, we present a patient with similar condition associated with biallelic mutations in FARSA (NM_004461.3: c.766T>C:p.Phe256Leu and c.1230C>A:p.Asn410Lys). Both detected FARSA variants are ultrarare and predicted to be damaging by in silico programs. Furthermore, they are both located in the active site of phenylalanyl-tRNA synthetase (PheRS) with Asn410Lys directly affecting a residue forming the wall of the phenylalanine-binding pocket. Clinical features shared between our patient and the FARSB syndrome include ILD with cholesterol pneumonitis, growth delay, hypotonia, brain calcifications with cysts and liver dysfunction. Our findings indicate that a disease similar to a syndrome associated with FARSB defects can also be caused by biallelic FARSA mutations. These findings are consistent with molecular structure of PheRS which is a tetramer including both FARSA and FARSB proteins.