Digenic mutations involving both the BSND and GJB2 genes detected in Bartter syndrome type IV.

Bartter syndrome type IV, characterized by salt-losing nephropathies and sensorineural deafness, is caused by mutations of BSND or simultaneous mutations of both CLCNKA and CLCNKB. GJB2 is the primary causative gene for non-syndromic sensorineural deafness and associated with several syndromic sensorineural deafness. Owing to the rarity of Bartter syndrome, only a few mutations have been reported in the abovementioned causative genes. To investigate the underlying mutations in a Chinese patient with Bartter syndrome type IV, genetic analysis of BSND, CLCNKA, CLCNKB and GJB2 were performed by polymerase chain reaction and direct sequencing. Finally, double homozygous mutations c.22C > T (p.Arg8Trp) and c.127G > A (Val43Ile) were detected in exon 1 of BSND. Intriguingly, compound heterozygous mutations c.235delC (p.Leu79CysfsX3) and c.109G > A (p.Val37Ile) were also revealed in exon 2 of GJB2 in the same patient. No pathogenic mutations were found in CLCNKA and CLCNKB. Our results indicated that the homozygous mutation c.22C > T was the key genetic reason for the proband, and a digenic effect of BSND and GJB2 might contributed to sensorineural deafness. To our knowledge, it was the first report showing that the GJB2 gene mutations were detected in Bartter syndrome.

Identification and functional analysis of a novel mutation in the SOX10 gene associated with Waardenburg syndrome type IV.

Waardenburg syndrome type IV (WS4) is a rare genetic disorder, characterized by auditory-pigmentary abnormalities and Hirschsprung disease. Mutations of the EDNRB gene, EDN3 gene, or SOX10 gene are responsible for WS4. In the present study, we reported a case of a Chinese patient with clinical features of WS4. In addition, the three genes mentioned above were sequenced in order to identify whether mutations are responsible for the case. We revealed a novel nonsense mutation, c.1063C>T (p.Q355*), in the last coding exon of SOX10. The same mutation was not found in three unaffected family members or 100 unrelated controls. Then, the function and mechanism of the mutation were investigated in vitro. We found both wild-type (WT) and mutant SOX10 p.Q355* were detected at the expected size and their expression levels are equivalent. The mutant protein also localized in the nucleus and retained the DNA-binding activity as WT counterpart; however, it lost its transactivation capability on the MITF promoter and acted as a dominant-negative repressor impairing function of the WT SOX10.

Osteopontin expression in nasopharyngeal carcinoma: its relevance to the clinical stage of the disease.

PURPOSE: To investigate osteopontin (OPN) expression in human nasopharyngeal carcinoma (NPC) and evaluate its clinical significance in the disease. MATERIALS AND METHODS: The expression of OPN mRNA in 44 frozen NPC tissue and 15 normal nasopharyngeal epithelium tissue (NNET) samples was examined by semi-quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). OPN protein expression in 67 paraffin-embedded NPC tissue and 21 NNET samples was detected by immunohistochemistry (IHC). In addition, OPN expression was investigated in 12 paired NPC and para-carcinoma tissue (PCT) samples by western blotting (WB). The association between the expression of OPN and the clinicopathologic parameters of NPC was evaluated. RESULTS: Three different methods all showed that the expression of OPN mRNA or protein in NPC was significantly higher than in NNET or PCT (P = 0.000, 0.001, 0.000, respectively). After an examination by IHC, 88.1% (59/67) of NPC samples showed strong or moderate positive OPN staining and 28.6% (6/21) of NNET samples displayed a weak positive OPN staining. The staining of OPN in tumor cells was mainly localized to the cytoplasm. OPN expression in NPC was not related to patient age or sex (P > 0.05), but was significantly related to tumor size, regional lymph nodal metastasis, and NPC clinical stages (P < 0.05). CONCLUSIONS: Our study demonstrated that OPN mRNA and protein overexpression in NPC may be important in the pathogenesis of the disease. It was strongly related to T stage, N stage and clinical stages of NPC, suggesting that OPN may be involved in NPC metastasis and progression.

Identification of Galectin-1 as a novel biomarker in nasopharyngeal carcinoma by proteomic analysis.

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors in southern China and Southeast Asia. It is characterized as a multistep process involved in multiple genetic and epigenetic events. The mechanism of carcinogenesis still needs to be further clarified. In this study, two-dimensional gel electrophoresis, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), RT-PCR, Western blot and immunohistochemical (IHC) analyses were used to detect Galectin-1 expression in NPC compared with normal nasopharyngeal epithelial tissues (NNET). We found that Galectin-1 was expressed at a significantly higher level in NPC compared with NNET. Our results indicated that high expression level of Galectin-1 might correlate with the development of NPC and Galectin-1 may serve as a potential diagnostic marker or therapeutic target for NPC.