Clinical features of children with lysinuric protein intolerance and SLC7A7 gene mutation: an analysis of 3 cases / 中国当代儿科杂志

Lysinuric protein intolerance (LPI) is an autosomal recessive disorder caused by SLC7A7 gene mutation and often involves severe lesions in multiple systems. Lung involvement is frequently seen in children with LPI and such children tend to have a poor prognosis. This article summarizes the clinical manifestations and gene mutation characteristics of three children diagnosed with LPI by SLC7A7 gene analysis. All three children had the manifestations of aversion to protein-rich food after weaning, delayed development, anemia, hepatosplenomegaly, and osteoporosis, as well as an increase in orotic acid in urine. In addition, interstitial pneumonia and diffuse pulmonary interstitial lesions were observed in two children. SLC7A7 gene detection showed three pathogenic mutations in these children, namely c.1387delG(p.V463CfsX56), c.1215G>A(p.W405X) and homozygous c.625+1G>A. After a definite diagnosis was made, all three children were given a low-protein diet and oral administration of citrulline [100 mg/(kg.d)], iron protein succinylate [4 mg/(kg.d)], calcium and zinc gluconates oral solution (10 mL/day) and vitamin D (400 IU/day). In addition, patient 3 was given prednisone acetate (5 mg/day). The children had varying degrees of improvement in symptoms and signs. It is hard to distinguish LPI from urea cycle disorder due to the features of amino acid and organic acid metabolism in LPI, and SLC7A7 gene analysis is the basis for a definite diagnosis of LPI.

The First Korean Case of Lysinuric Protein Intolerance: Presented with Short Stature and Increased Somnolence

Lysinuric protein intolerance (LPI) is a rare inherited metabolic disease, caused by defective transport of dibasic amino acids. Failure to thrive, hepatosplenomegaly, hematological abnormalities, and hyperammonemic crisis are major clinical features. However, there has been no reported Korean patient with LPI as of yet. We recently encountered a 3.7-yr-old Korean girl with LPI and the diagnosis was confirmed by amino acid analyses and the SLC7A7 gene analysis. Her initial chief complaint was short stature below the 3rd percentile and increased somnolence for several months. Hepatosplenomegaly was noted, as were anemia, leukopenia, elevated levels of ferritin and lactate dehydrogenase, and hyperammonemia. Lysine, arginine, and ornithine levels were low in plasma and high in urine. The patient was a homozygote with a splicing site mutation of IVS4+1G > A in the SLC7A7. With the implementation of a low protein diet, sodium benzoate, citrulline and L-carnitine supplementation, anemia, hyperferritinemia, and hyperammonemia were improved, and normal growth velocity was observed.