A RHAG point mutation selectively disrupts Rh antigen expression.

OBJECTIVES: The aim of this study was to characterise a novel mutation in the gene encoding RhAG in order to elucidate a molecular mechanism for Rh antigen expression and spherocytosis. BACKGROUND: Rhesus-associated glycoprotein (RhAG) is critical for maintaining the structure and stability of erythrocytes. Single missense mutations in the gene encoding RhAG are sufficient to induce spherocytosis and deficiencies in Rh complex formation. We report a novel missense mutation that incompletely disrupts Rh antigen expression and selectively knocks out RhD antigen expression. METHODS: Blood samples were taken from a 38-year-old male, his brother, his wife and his daughter in Xi'an, China. To detect the proband's RhAG and D antigen expression, the RBC were stained with anti-D and anti-RhAG and analysed by flow cytometry. Red blood cell morphology was detected with atomic force microscopy (AFM). Genomic DNA was isolated from whole blood samples, and the RHD, RHCE and RHAG alleles were sequenced and analysed. The mutation was mapped onto a predicted crystal structure of RhAG by the I-TASSER server and visualised using PyMOL. RESULTS: Morphological testing by AFM found clear evidence of spherocytosis in the proband's erythrocytes. RHAG gene sequencing identified the mutation at sequence 236G > A, resulting in a serine to asparagine substitution at residue 79 (S79N). Family survey indicated that inheriting this allele is necessary and sufficient to cause the condition. Mapping the mutation onto a predicted crystal structure of RhAG revealed the proximity of the mutation to the critical structural elements of the protein. CONCLUSIONS: A novel RHAG mutation significantly lowers RhAG antigen expression and antigen-mediated agglutination intensity.

[A pilot study on arsenic removal facilities for central supply of drinking water].

In order to promote the application and industrialization of an arsenic removal agent developed in this project, and to improve the technology, it is necessary to have a median sized facility to test the effects, capacity and regeneration of the agent. A facility with the capacity of 1 m3/h for arsenic removal was installed in a bottled water plant, which has been operated since April 1999. The results showed that the arsenic content of effluent water has met the requirement of the national standard for drinking water. The effect of arsenic removal was by 2 mg/g. The annual cost per person was only 1.46 Yuan RMB. The operation and maintenance of the facility was simple and no need to adjust the pH of influents and effluents. The chemical regenerative agent was safe, low cost and effective. Therefore, the facility can be used in rural areas and the water plants while the arsenic in source water was higher than 0.05 mg/L.