Effects of a chemical chaperone on genetic mutations in alpha-galactosidase A in Korean patients with Fabry disease

Fabry disease is an X-linked inborn error of glycosphingolipid catabolism that results from mutations in the gene encoding the alpha-galactosidase A (GLA) enzyme. We have identified 15 distinct mutations in the GLA gene in 13 unrelated patients with classic Fabry disease and 2 unrelated patients with atypical Fabry disease. Two of the identified mutations were novel (i.e., the D231G missense mutation and the L268delfsX1 deletion mutation). This study evaluated the effects of the chemical chaperones 1-deoxygalactonojirimycin (DGJ) on the function of GLA in vitro, in cells containing missense mutations in the GLA gene. Nine missense and a nonsense mutations, including one novel mutation were cloned into mammalian expression vectors. After transient expression in COS-7 cells, GLA enzyme activity and protein expression were analyzed using fluorescence spectrophotometry and Western blot analysis, respectively. DGJ enhanced GLA enzyme activity in the M42V, I91T, R112C and F113L mutants. Interestingly, the I91T and F113L mutations are associated with the atypical form of Fabry disease. However, DGJ treatment did not have any significant effect on the GLA enzyme activity and protein expression of other mutants, including C142W, D231G, D266N, and S297F. Of note, GLA enzyme activity was not detected in the novel mutant (i.e., D231G), although protein expression was similar to the wild type. In the absence of DGJ, the E66Q mutant had wild-type levels of GLA protein expression and approximately 40% GLA activity, indicating that E66Q is either a mild mutation or a functional single nucleotide polymorphism (SNP). Thus, the results of this study suggest that the chemical chaperone DGJ enhances GLA enzyme activity and protein expression in milder mutations associated with the atypical form of Fabry disease.

Genetic Analysis of TGFA, MTHFR, and IFR6 in Korean Patients Affected by Nonsyndromic Cleft Lip with or without Cleft Palate (CL/P)

Nonsyndromic cleft lip with or without cleft palate (CL/P) is a common craniofacial birth defect that is the result of a mixture of genetic and environmental factors. While studies have identified a number of different candidate genes and loci for the etiology of CL/P, the results have not been consistent among different ethnic groups. To study the genetic association of the candidate genes in Korean patients affected by CL/P, we genotyped 97 nonsyndromic CL/P patients and 100 control individuals using single nucleotide polymorphic markers at the MTHFR, TGFA, and IRF6 genes. We report that the T3827C marker at TGFA showed significant association with nonsyndromic CL/P, but all the other markers tested were not significantly associated with nonsyndromic CL/P in Korean patients.

A Case of Spontaneous Mediastinal Hemorrhage in Patients on Chronic Hemodialysis / 대한신장학회잡지

Spontaneous hemorrhage in the patients undergoing hemodialysis is the ralatively common problem, but spontaneous mediastinal hemorrhage in such patients reported only few cases. We experienced a case of spontaneous mediastinal hemorrhage in chronic hemodialysis patient who complained of continuous pleuritic chest pain and mild dyspnea. The diagnosis was made dy chest computed tomography,magnetic resonance imaging and percutaneous fine needle aspiration of liquified dark reddish old blood material guided by ultrasonography. Treatment is usually conservative, with blood volume replacement and intensive hemodialysis using regional heparinization. We report on a patient undergoing hemodialysis due to endstage renal disease who developed spontaneous mediastinal hemorrhage.