Ferreira H, Seppala R, Pinto R, Huizing M, Martins E, Braga A C, Gomes L, Krasnewich D M, Sa Miranda M C, Gahl W A
Departamento de Pediatria, Hospital Maria Pia, Porto, Portugal.
Mol Genet Metab. 1999 Jun;67(2):131-7. doi: 10.1006/mgme.1999.2852.
Sialuria, a disorder of sialic acid (NeuAc) metabolism characterized by increased free NeuAc in the cytoplasm of cells, is due to failure of CMP-Neu5Ac to feedback inhibit UDP-N-acetylglucosamine (UDP-GlcNAc) 2-epimerase. We now describe the fifth patient in the world with sialuria, a 7-year-old Portuguese girl with developmental delay, hepatomegaly, coarse facies, and urinary excretion of 19 micromol of free NeuAc/mg creatinine. The patient's fibroblasts stored excess free NeuAc in the cytosolic fraction, and fibroblast UDP-GlcNAc 2-epimerase activity was only 26% inhibited by 100 microM CMP-Neu5Ac (normal, 79%). The patient's UDP-GlcNAc 2-epimerase gene displayed an R266Q mutation in only one allele, consistent with known sialuria mutations and with the proposed dominant nature of this disorder. Extensive description of sialuria patients will help to define the clinical and biochemical spectrum of this disease.
唾液酸尿症是一种唾液酸（NeuAc）代谢紊乱疾病，其特征是细胞胞质中游离NeuAc增加，这是由于CMP-Neu5Ac无法反馈抑制UDP-N-乙酰葡糖胺（UDP-GlcNAc）2-表异构酶所致。我们现在描述世界上第五例唾液酸尿症患者，一名7岁的葡萄牙女孩，有发育迟缓、肝肿大、面容粗糙，尿中游离NeuAc排泄量为19微摩尔/毫克肌酐。该患者的成纤维细胞在胞质部分储存了过量的游离NeuAc，且成纤维细胞UDP-GlcNAc 2-表异构酶活性仅被100微摩尔/升CMP-Neu5Ac抑制26%（正常为79%）。该患者的UDP-GlcNAc 2-表异构酶基因仅在一个等位基因中出现R266Q突变，这与已知的唾液酸尿症突变以及该疾病的显性特征相符。对唾液酸尿症患者的详细描述将有助于明确该疾病的临床和生化谱。
