1206

Abstract

Introduction: A 2-month-old male was transferred to the pediatric intensive care unit after 1 month hospitalization in several other institutions. He had failure to thrive, vomiting, diarrhea, hypoglycemia, metabolic acidosis, and elevated liver enzymes. He had tachypnea, which had been explained as a compensatory to the degree of metabolic acidosis. The working diagnosis was inborn error of metabolism, but initial testing failed to reveal the diagnosis and the metabolic team signed off. Upon review of his chest radiography, absence of a thymus shadow was noted, as was interstitial pneumonitis. Bronchoscopy was performed; bronchoalveolar lavage indicated pneumonia due to Pneumocystis jirovecii. Appropriate therapy was initiated. Further tests for immunodeficiency remained puzzling as no primary immunodeficiency syndrome could be identified. The metabolic team was involved again and testing for congenital disorder of glycosylation (CDG) was sent, given a few reports of associated immunodeficiency. Final result of chromosomal analysis showed two phosphomannomutase 2 (PMM2) gene mutations, consistent with CDG Ia. Despite initial improvement (11 days of extubation and enteral feeds), clinical deterioration occurred (pleural and pericardial effusions and acute respiratory failure). He had worsening renal function and oliguria; he also developed seizures. Ultimately, the family opted to withdraw care. PMM2-CDG, or CDG Ia, is the most common disorder of N-linked glycosylation defects. Patients with CDG Ia exhibit clinical variability: they may present as neonates with hydrops, pericardial effusion, ascites, and death; or they may present later in infancy with hypotonia, dysmorphic features, and developmental delay. Milder phenotypes have been described. A case series detailed the spectrum of CDG Ia phenotypes, further categorizing them into neurological and multivisceral subtypes. None of these patients exhibited lung involvement or immunodeficiency. Our patient presented with an opportunistic infection and immune dysfunction, likely secondary to his underlying CDG Ia. To the best of our knowledge, infection with Pneumocystis jirovecii pneumonia in this context has not previously been described.