Search

Introduction Pulmonary alveolar proteinosis (PAP) is defined by increased accumulation of surfactant in the alveolar space. PAP has been reported to be associated with a large number of clinical conditions and diseases. Whole lung lavages can be helpful to stabilize the clinical course of PAP until the underlying condition is identified, which may enable more specific treatment. Recently, heterozygous OAS1 gain-of-function variants were described as cause in a patient with infantile-onset PAP combined with hypogammaglobulinemia. Case presentation At age 4 months, a female infant born to term was diagnosed with hypogammaglobulinemia and treated with monthly immunoglobulin injections. At age 15 months, the girl needed supplemental oxygen at night, and at age 18 months, also during the day. At age 2 years, pulmonary alveolar proteinosis of unknown etiology was diagnosed by computed tomography scan and open lung biopsy. Subsequently, monthly whole lung lavages (WLLs) were started, which stabilized the clinical course for over 2 years until a disease-causing OAS1 variant was diagnosed and the patient was successfully treated by hematopoietic stem cell transplantation. Conclusion Here, we describe the successful management of a female patient with severe PAP caused by a heterozygous OAS1 gain-of-function variant until a definitive diagnosis was made and cured by hematopoietic stem cell transplantation. This article is protected by copyright. All rights reserved.

Background: Pulmonary alveolar proteinosis (PAP) is a heterogeneous condition with more than 100 different underlying disorders that need to be differentiated to target therapeutic options, which are generally limited. Methods: The clinical course of two brothers with pathogenic variants in the methionyl-tRNA synthetase (MARS)1 gene was compared to previously published patients. Functional studies in patient-derived fibroblasts were performed and therapeutic options evaluated. Results: The younger brother was diagnosed with PAP at the age of 1 year. Exome sequencing revealed the homozygous MARS1 variant p.(Arg598Cys), leading to interstitial lung and liver disease (ILLD). At 2 years of age, following surgery hypoglycemia was detected, the pulmonary condition deteriorated, and the patient developed multiorgan failure. Six therapeutic whole lung lavages (WLL) were necessary to improve respiratory insufficiency. Methionine supplementation was started and a high protein diet ensured, leading to complete respiratory recovery. The older brother, homozygous for the same MARS1 variant, had a long-known distinct eating preference of methionine-rich food and showed a less severe clinical phenotype. Decreased aminoacylation activity confirmed the pathogenicity of p.(Arg598Cys) in vitro. In agreement with our review of currently published ILLD patients, the presence of hepatopathy, developmental delay, muscular hypotonia, and anemia support the multisystemic character of the disease. Conclusions: Catabolic events can provoke a severe deterioration of the pulmonary situation in ILLD with a need for repetitive WLL. Although the precise role of oral methionine supplementation and high protein intake are unknown, we observed an apparent treatment benefit, which needs to be evaluated systematically in controlled trials.