Laron Syndrome (LS), (OMIM# 262500), a rare recessively inherited disease caused by deletions or mutations of the GH receptor, gene characterized by dwarfism with low or undetectable serum IGF-I in the presence of high serum GH. In addition to dwarfism, the IGF-I deficiency leads to metabolic abnormalities including aberrations in protein biosynthesis and homeostasis. The only available treatment for LS patients is (r)IGF-I administration.

The present study was aimed to determine the plasma concentrations of specific amino acids and their metabolites in the blood of untreated and IGF-I-treated LS patients.

The study involved a total of 10 LS patients (3 untreated and 7 treated), 2 heterozygote mothers and 3aged subjects. Forty healthy boys and girls served as controls.

The analysis of amino acids and their metabolites was performed using the LC-MS/MS analysis and Waters Acc-Q Tag ultra-derivatization kit. Serum IGF-I levels were measured by a one-step sandwich chemiluminescence immunoassay.

The results revealed that long-term IGF-I deficiency in LS patients led to abnormal changes in the plasma amino acids metabolism, such as low levels of plasma citrulline, sarcosine and taurine that increased upon IGF-I replacement. The plasma amino acid levels of the heterozygous family members resembled those of the untreated LS patients, whereas the pattern in the 2 double heterozygote sisters previously treated with IGF-I resembled that of the presently IGF-I-treated patients. In addition, plasma ɑ-amino adipic acid levels were elevated in both untreated and IGF-I-treated patients.

In summary our data revealed that LS patients, a condition associated with congenital IGF-I deficiency, have an abnormal plasma amino acid metabolism that is partially restored by IGF-I treatment.

Laron综合征（LS）（OMIM＃262500）是一种罕见的隐性遗传疾病，由GH受体的缺失或突变引起，该基因的特征是在高血清GH存在的情况下，血清IGF-I低或无法检测的侏儒症。除侏儒症外，IGF-I缺乏症还会导致代谢异常，包括蛋白质生物合成和体内稳态的异常。LS患者唯一可用的治疗方法是（r）IGF-I给药。

本研究旨在确定未经治疗和经IGF-I治疗的LS患者血液中特定氨基酸及其代谢产物的血浆浓度。

该研究共涉及10名LS患者（3名未经治疗和7名接受治疗），2名杂合子母亲和3名年龄较大的受试者。40名健康的男孩和女孩作为对照。

使用LC-MS / MS分析和Waters Acc-Q Tag超衍生试剂盒对氨基酸及其代谢产物进行分析。血清IGF-I水平通过一步式夹心化学发光免疫测定法测量。

结果显示，LS患者的长期IGF-I缺乏症导致血浆氨基酸代谢异常变化，例如血浆瓜氨酸，肌氨酸和牛磺酸水平低，而IGF-I替代则增加。杂合家族成员的血浆氨基酸水平类似于未治疗的LS患者的血浆氨基酸水平，而先前用IGF-I治疗的2个双杂合子姐妹的模式类似于当前IGF-I治疗的患者。另外，未经治疗和经IGF-I治疗的患者血浆α-氨基己二酸水平均升高。

总之，我们的数据显示，与先天性IGF-1缺乏症相关的LS患者的血浆氨基酸代谢异常，通过IGF-1治疗可以部分恢复。