Children with lysinuric protein intolerance: Experience from a lower middle income country.

Background: Lysinuric protein intolerance (LPI) is an inborn error of metabolism consequential to recessive mutations in the SLC7A7 gene. The metabolic imbalance in absorption and excretion of dibasic amino acids is considered the basis of LPI. The disease results from protein intolerance with signs and symptoms oscillating from cerebral impairment, respiratory involvement, renal failure and autoimmune complications.

Aim: To determine biochemical and clinical presentation of cases with biochemical picture suggestive of LPI in Pakistani children.

Methods: The study was conducted at the Biochemical Genetic Lab, Department of Pathology and Laboratory Medicine, AKU Plasma, and urine amino acid quantification data from January 2013 to October 2018 was included in this study. The amino acids were analyzed by high performance liquid chromatography. Prestructured requisition forms were used to obtain the clinicopathological data. Statistical analysis was done by Microsoft Excel 2017.

Results: A total of 6 patients were recognized. All the patients were male (100%). The mean age was 24 mo ± 10 d. All the patients had low plasma concentration of lysine, ornithine and arginine, whereas increased levels of lysine, ornithine and arginine in urine were observed in 2 patients. History of consanguineous marriage was present in all patients (100%). The most observed clinical symptom was feeding difficulty followed by failure to thrive (83.3%) and developmental delay (66.6%). Hepatomegaly was present in all patients (100%). No mutation analysis was done.

Conclusion: This study portrays the biochemical and clinical spectrum of LPI in Pakistan. Although clinical manifestations appeared in the first 2 years of life, most of them suffered a delay in undergoing diagnostic workup.