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.
赖氨酸尿性蛋白耐受不良（LPI）是由SLC7A7基因突变引起的一种常染色体隐性遗传病，常常累及多个系统病变，肺部受累较为常见，儿童患者预后差。该文总结3例经SLC7A7基因分析确诊为LPI患儿的临床表现和基因突变特点。3例患儿均表现为断乳后不喜蛋白饮食、生长发育落后、贫血、肝脾肿大、骨质疏松等，均有尿乳清酸增高。2例表现有间质性肺炎、弥漫性肺间质病变。SLC7A7基因检测结果显示3例患儿中共检测出3种致病突变：c.1387delG（p.V463CfsX56）、c.1215G > A（p.W405X）和纯合c.625+1G > A。3例患儿诊断明确后，予低蛋白饮食，口服瓜氨酸100 mg/（kg·d）、蛋白琥珀酸铁4 mg/（kg·d）、葡萄糖酸钙锌10 mL/d、维生素D 400 IU/d，例3还予醋酸泼尼松5 mg/d治疗，症状和体征均有不同程度改善。LPI的氨基酸和有机酸代谢特点与尿素循环障碍较难鉴别，SLC7A7基因分析是LPI确诊的依据。