Mutation analysis of common deafness genes among 1,201 patients with non-syndromic hearing loss in Shanxi Province.

BACKGROUND: Hearing impairment is one of most frequent birth defects, which affects nearly 1 in every 1,000 live births. However, the molecular etiology of non-syndromic deafness in China is not well studied. Here, we have investigated the presence of mutations in three genes commonly mutated in non-syndromic deafness patients in Shanxi Province, which has the highest frequency of birth defects in China. METHODS: In total, 1,201 unrelated non-syndromic deafness patients and 300 healthy individuals were enrolled. The hearing ability was confirmed by audiologic evaluation. Three major deafness-related genes (GJB2, SLC26A4 (PDS), and mtDNA 12S rRNA) of all individuals enrolled were analyzed by Sanger sequencing. RESULTS: The results showed that GJB2 mutations accounted for 21.23% (255/1,201) in the patient group, with c.235delC, a hotspot mutation, accounting for 10.99% (132/1,201). Moreover, 11 new GJB2 mutations were identified. SLC26A4 mutations accounted for 9.33% (112/1,201) in the patient group, with IVS7-2A>G as the most prevalent mutation accounting for 4.75% (57/1,201). In addition, 15 patients (1.25%) were found to carry mtDNA 12S rRNA c.1555A>G mutation, while only two cases had the mtDNA 12S rRNA c.1494C>T. CONCLUSION: In our research, it was found that c.235delC in GJB2 and c.919-2A>G (IVS7-2A>G) in SLC26A4 were the highest frequency pathogenic variants in Shanxi Province. Taken together, our data will enrich the database of deafness mutations and will help clinical diagnosis, treatment, and genetic counseling of hearing impairment.

Improvement of a potential anthrax therapeutic by computational protein design.

Past anthrax attacks in the United States have highlighted the need for improved measures against bioweapons. The virulence of anthrax stems from the shielding properties of the Bacillus anthracis poly-γ-d-glutamic acid capsule. In the presence of excess CapD, a B. anthracis γ-glutamyl transpeptidase, the protective capsule is degraded, and the immune system can successfully combat infection. Although CapD shows promise as a next generation protein therapeutic against anthrax, improvements in production, stability, and therapeutic formulation are needed. In this study, we addressed several of these problems through computational protein engineering techniques. We show that circular permutation of CapD improved production properties and dramatically increased kinetic thermostability. At 45 °C, CapD was completely inactive after 5 min, but circularly permuted CapD remained almost entirely active after 30 min. In addition, we identify an amino acid substitution that dramatically decreased transpeptidation activity but not hydrolysis. Subsequently, we show that this mutant had a diminished capsule degradation activity, suggesting that CapD catalyzes capsule degradation through a transpeptidation reaction with endogenous amino acids and peptides in serum rather than hydrolysis.