Background: Lysinuric protein intolerance (LPI) is a metabolic disorder resulting from mutations in SLC7A7 gene that is inherited as autosomal recessive. The disease has been described sporadically worldwide, including a few cases from Arab countries. The affected patients typically present with failure to thrive (FTT), hepatosplenomegaly and protein intolerance. Various complications such as autoimmune disorders, infiltrative lung disease, hemophagocyticlymphohistiocytosis (HLH) and neurological manifestations could be noted during the disease course.   
Method:  We described patients diagnosed with LPI in Bahrain by reviewing their presentations, complications encountered, genetic variability and treatment options.
Results: Four patients two males and two females from three families with an age range between 2-14 years were followed. Failure to thrive and HLH were the main presenting features in all patients. Two novel mutations were detected in SLC7A7 gene.  One of them is a homozygous splice site mutation of c. 1429+1G>. , while the second mutation, is a homozygous missense mutation of c.168T>G p.(Phe56Leu). Lung complications were found in two patients, autoimmunity observed in two patients, gastrointestinal presenting as hemorrhagic gastritis in one patient and neurological complications were seen in one patient.
Conclusion: The main presenting feature in all of our patients was HLH. Two novel mutations in SLC7A7 gene were detected. Rheumatological complications were variable within the same family members; moreover, hemorrhagic gastritis is reported in one of our patients as a new possible complication related to the disease.
Keywords: Lysinuric protein intolerance, Hemophagocyticlymphohistiocytosis, Pulmonary alveolar proteinosis, Osteoporosis, Hemorrhagic gastritis 
Abbreviations: Lysinuric protein intolerance (LPI), Failure to thrive (FTT), Hemophagocyticlymphohistiocytosis (HLH)