The Great Masquerade: Varying Manifestations of Lysinuric Protein Intolerance

Lysinuric protein intolerance (LPI) is an inborn metabolic error caused by cationic amino acid transport defects. The disease has a significant degree of phenotypic variation, with no confirmed genotype-phenotype correlation. Because it presents with symptoms similar to far more common diseases, the diagnosis is often missed, resulting in increased morbidity and mortality. This case series describes three examples of LPI with pulmonary, neurological, and immunological manifestations, emphasising the importance of keeping this disorder on the differential list. Appropriate metabolic and genetic testing is important in providing the correct diagnosis and timely care in such cases.